When first reading this thread, I started to think that my position on pronouncing letters vs. making words from acronyms was inconsistent. However, the more I look at some of the examples, I've figured out that I actually have an algorithm in my head that governs this selection process. I don't know all of the coefficients and fudge factors in the equation, but in general, my likelihood of making a word out of an acronym:

- varies in proportion to how much shorter that word is (in syllables) compared to spelling the letters out
- varies inversely with how goofy that word sounds when pronounced

Of course, Linux, Debian, etc. aren't subject to this policy, only things like EXE and SQL. For instance, SQL is 33% shorter than "S Q L" and sounds like a real word ("sequel") so I use it. "Eggsy" or "ecksie" are the same 33% shorter, but they both sound goofy, so I spell out "E X E."

"Com" instead of "C O M" (as in COMMAND.COM) is a no-brainer, because it's 66% shorter and doesn't sound goofy at all. Others that fall into this category for me are "ping" for PNG and "jay-peg" for JPG.

One additional note is that when a letter can produce multiple different sounds (such as a hard and soft consonant sound) I always try to make sure that sound is reflected in the word made from the letters. So GIF files are "giff" not "jiff" because it's not the Compuserve Giraffe Interchange Format (although that would probably make a great Gary Larson cartoon.)

"Earl" or "URL" is an interesting one. To me, it sounds goofy, because it's a guy's name. ("Who's Earl?") In addition, the U stands for Universal, which begins with more of a Y sound ("yooniversal") than any kind of U vowel sound. These two strikes against it lead me to sound out "U R L" despite its comparative awkwardness.

One of the toughest calls is "dub dub dub" vs. "W W W". The former is 33% in terms of syllables, but sounds absolutely retarded. The goofiness loses in the end, and I go with the 9-syllable monstrosity known as "W W W." (The compromise, "dubya dubya dubya" is out of bounds for me due to similarities to... well, some moron from Texas.)

Anyway, I'm sure if I thought long enough I could think of examples which break these criteria, especially as the acronyms get longer... But that's my story, and I'm sticking to it.