The $51 billion in cash and marketable securities that Apple (AAPL) reported last Monday — double its holdings two years ago (see chart)  — has been burning a hole ever since in everybody’s pocket but Steve Jobs’.

The next day, the business press was full of stories quoting Jobs’ answer about why Apple doesn’t pay dividends — “we like to keep our powder dry” for those “one or more very strategic opportunities [that] may come along” — and suggesting what headline-grabbing purchases he might make with all that money.

The
New York Times
had a list that included Netflix (NFLX), Electronic Arts (ERTS) and Facebook (privately held). Readers of Barrons’ Tech Trader Daily weighed in with Adobe (ADBE), Yahoo (YHOO), Sirius XM (SIRI), TiVo (TIVO), SanDisk (SNDK) and Disney (DIS).

[The latest rumor, which drove shares of Sony (SNE) up nearly 3% in Asian markets Tuesday, is that Apple is thinking about buying the company that invented the Walkman. Jobs may have once admired Sony but, as Asymco‘s Horace Dediu points out, “the company today contains nothing of value to Apple.”]

This is all nonsense.

First, by “strategic opportunities,” Jobs does not necessarily mean mergers and acquisitions. He might be talking about building something, say another giant server farm like the one set to open in North Carolina.

Second, if he were to buy a company, it would not be Facebook — a name that came up again over the weekend before Facebook PR felt obliged to shoot down rumors that it was about receive a giant infusion of cash from Apple.

Social network companies that know nothing about building products and have not yet figured out how to monetize what they do have are not the kind of enterprise that Apple buys.

What kind of enterprise does Apple buy? The list below, taken from Wikipedia, is instructive. As the entry succinctly puts it, paraphrasing BusinessWeek‘s Arik Hesseldahl: “Apple’s business philosophy is to acquire small companies that can be easily integrated into existing company projects.”

For example:

• 1997 Next (programming services). Value: $404 million
• 1997 Power Computing (cloned computers). $100 million
• 1999 Xemplar Education (software). $5 million
• 1999 Raycer Graphics (graphic chips). $15 million
• 2000 NetSelector (Internet software). Value: NA
• 2001 Astarte (DVD authoring software). Value: NA
• 2001 bluebuzz (Internet service provider). Value: NA
• 2001 Source Technologies (graphics software). Value: NA
• 2001 PowerSchool (online info systems services). $62 million
• 2002 Nothing Real (special effects software). $15 million
• 2002 Zayante (software). $13 million
• 2002 Silicon Grail Corp-Chalice (digital effects software). Value: NA
• 2002 Emagic (music production software). $30 million
• 2002 Propel Software (software). Value: NA
• 2005 Fingerworks (gesture recognition). Value: NA
• 2006 Silicon Color (software). Value: NA
• 2006 Proximity (software). Value: NA
• 2008 P.A. Semi (semiconductors). $268 million
• 2009 Placebase (maps). Value: NA
• 2009 Lala (music streaming). $17 million
• 2010 Quattro (mobile advertising). $275 million
• 2010 Intrinsity (semiconductors). $121 million
• 2010 Siri (software). Value: NA
• 2010 Poly9 (Web-based mapping). Value: NA

See? Not a Facebook, Disney or Sony among them. And the largest acquisition — by far — was the 1997 purchase of NeXT that brought Steve Jobs back to Apple.

See also:

• What Apple has bought, and what it hasn’t
• Steve Jobs as Scarlett O’Hara

[Follow Philip Elmer-DeWitt on Twitter @philiped]