Sperber--
Don't worry, you're hardly alone!!! Trust me, no matter how crazy you get, there will always be someone crazier. Personally, I stick to CD singles, and I've got all of 'em from beginning to end, pretty much... I was lucky enough to get interested in U2 in the early 90's when they still had tons of the special import editions of all the 80's singles on CD, which are now out of print. That stopped mattering so much when the b-sides disc with the Best Of came out, though. But, still, I mainly collect just for listening to the b-sides, so if a CD single is made up entirely of songs I already have, I often don't buy it.
Singles are the best!!! Better than promos because you don't have to scramble to find them or suck up to DJ's and record store owners, but they're still official so you get more U2 than what's on the albums in a legit way!
------------------
you've got the right shoes to get you through the night