Steve Jobs' abrupt exit as chief executive of Apple Inc. has rocked Wall Street and Silicon Valley. The man known for his aesthetic and eye for detail and emphasis on sleek, easy to use products turned Apple from near bankruptcy into the world's second most valuable company. But Apple was Steve Jobs, and Jobs was Apple. Without Jobs' vision, leadership and charisma, the successor has the daunting task of equaling the bar set by Jobs: help create the 21st century.

People are now asking -- who will be the next Steve Jobs?

Here a short list of the multi-billion dollar tech firms and the persons running the show:

Apple Inc. (market value: $346 billion). Timothy D. "Tim" Cook, 50, was handpicked by Jobs as replacement after the latter resigned as on Aug. 24. A fitness enthusiast, Cook has huge shoes to fill -- after all Jobs turned Apple into the world's most valuable technology company with innovative products that were unique in a competitive marketplace (iPod, iPhone and iMac) and new cash cows (iPad, and iTunes). After stints with IBM and Compaq, Cook joined Apple in March 1998 and was interim CEO when Jobs was on medical leave. Cook has emphasized the importance of intuition in guiding his life's biggest choices. Apple posted record revenue of $28.57 billion and record net profit of $7.31 billion for the past quarter (yes, not year) and those figures will likely keep up in the time ahead. Ask Cook a simple question -- like, What's next for Apple after iPad 3 and iPhone 5? It's OK that he won't be a control freak like Jobs, but hopefully he retains Jobs' charisma.

Microsoft Corp. ($206 billion). Steven Ballmer, 55, has held the post of chief executive officer of Microsoft since January 2000. Although Microsoft has seen softening sales of its flagship Windows operating system and has not penetrated the smartphone market, Microsoft continues to be a highly profitable company. Bill Gates, co-founder and chairman of Microsoft, need not return as chief executive, as Microsoft under Ballmer has continued to post a double digit growth despite a challenging environment. Microsoft has kept its U.S. triple-A ratings from Standard & Poor's, making it the only tech firm that's rated higher than the U.S. federal government (though Apple would also be on the triple-A club if it was rated). For the fiscal year ended June 30, 2011, Microsoft reported record revenue of $69.94 billion, a 12% increase from the prior year. Net income was $23.15 billion, which represented a 23 percent increase from the previous year.

International Business Machines Corp. ($197 billion). Samuel J. Palmisano, 60, has served as CEO since March 2002 and chairman since 2003. Under Palmisano, IBM sold the low-margin personal computer business to Lenovo for $1.75 billion, and transformed itself to one of the largest information technology and consulting firms. IBM is now one of the most profitable companies in the world (7th most, according to Forbes). Palmisano, who started as a salesman at IBM in 1973, turned 60 last month but said he has no plans to retire.

Google Inc. ($168 billion). Lawrence "Larry" Page, 38, co-founded Google and took the role as CEO in April this year. The University of Michigan and Stanford University Alum has been busy this year trying to transcend Google beyond its core web search engine -- Google recently signed a deal to buy Motorola Mobility for $12.5 billion (for defense in patent litigation) and in June launched the Google+ social network to fight against Facebook. While Google+ could end up as another social networking flop, Google's search engine is the world's number one web site; it owns YouTube, the number video sharing site; and it has Android, the most popular platform for smartphones.

Hewlett-Packard Company ($52 billion). Leo Apotheker, 57, took the role of CEO of HP in September 2010. Highly lauded for his work as co-CEO SAP AG, Apotheker became chief executive of the world's largest seller of desktops and laptops after CEO Mark Hurd was forced to resign after a sexual harassment controversy. Apotheker-led HP is undergoing its critical stages -- last week it announced that it is halting its mobile device operations just a year after HP paid $1.2 billion to acquire mobile products seller Palm, Inc. HP also announced that it is spinning of its market leading PC business, while continuing to sell servers and other equipment to business customers, was similar to what IBM did in 2005.

Facebook Inc. ($82 billion, as estimated by SharesPost). Mark Zuckerberg, 27, co-founded Facebook in 2004 and since then the social networking service has skyrocketed to more than 750 million users, making it the number one social network and one of the world's most popular Web site, second only to Google. Zuckerberg, as CEO, has been busy this time further improving Facebook to counter Google+'s growing popularity (the latest, putting Skype for video calling on FacebooK). He will be busier next year when Facebook is expected to launch its initial public offering. The IPO is expected to gross a record $100 billion.

Cisco Systems, Inc. ($83 billion). John T. Chambers, 62, for sixteen years has been the CEO of the most profitable manufacturer and seller of Internet protocol (IP)-based networking and other products. Diagnosed with Dyslexia, Chambers worked at Wang Laboratories and IBM before joining Cisco in 1991 as an executive. In 1995, at that the time he assumed the role as CEO, Cisco only had $1.2 billion in annual revenue. Now Cisco had $40 billion in revenue (a 10.9% increase from 2009), creating profit of $7.8 billion in year ended July 31, 2010. Investors and the 70,000 employees at Cisco surely want Chambers to run the company forever.
Amazon.com. Inc. ($87 billion). Jeffrey Preston "Jeff" Bezos, 47, founded Amazon in 1995 (from a business plan he created after flying/driving from New York to Seattle). Amazing book titles from A to Z, the online bookstore never made a profit until the first quarter of 2001. Since then, Preston led Amazon to emerge as the world's largest online retailer, selling everything from books, CDs, music, video games and electronic devices. Amazon had net profit of more than $2.6 billion on $78 billion of net sales in the past three years. The Princeton University graduate is known for his attention to business-process details.

ebay Inc.($36.5 billion). John Donahoe, 41, was named as CEO of eBay in March 2008, replacing Meg Whitman, who stepped down after 10 years. Under Donahoe, the world's largest auction Web site and payment unit Paypal have continued to expand worldwide. During Donahoe's helm, eBay sold Skype at a profit for $2.75 billion. In 2010, net income was $1.8 billion on revenue of $9.16 billion, which was up 5% from 2009. The holder of a B.A. in Economics from Dartmouth College and an M.B.A. degree from the Stanford Graduate School of Business will said last month that PayPal has surpassed 100 million active registered accounts and reported its first billion-dollar revenue quarter, and eBay growth in the U.S. is accelerating.

Nokia Oyj ($22 billion). Stephen Elop, 47, agreed to join Nokia in September 2010, agreeing to leave as head of Microsoft's business division after being offered a signing bonus of $6 million. While Elop inherited a company that has been the top seller of smartphones and cellphones in the past decade, it hasn't been good news for Elop since he took the role. Nokia could finally cede the no. 1 smartphone vendor spot to Apple Inc. or Samsung Electronics at the end of the year. As sales have been slumping and efforts with a new OS a dud (Meego), Nokia has faced credit downgrades and declining stock and has been forced to cut its workforce. Elop has asked shareholders to be patient: Nokia is currently undergoing transition -- it is retiring the Symbian platform -- but hopes to recover its market dominance when it starts releasing its Windows-based smartphones in the fourth quarter.

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