I try to keep a list for each project as well. This list will list tiles, scripts, and music I use. Honestly, I kind of skimp in the music department. I get 99% of my MIDIs from VGmusic, and just forget to write down the composer. Not to mention I've downloaded hundreds, maybe even thousands of MIDIs over the years, and keeping track of all that is just pretty much not happening on any level. If I get music from Pure, I'd credit it. I don't feel too bad about this, since it's not like I'm claiming it as my own, and the guy didn't compose the notes himself, so it's not infringing on his IP, assuming it is from an existing game (referring to VGmusic MIDIs here, not Pure).
As for my stuff, I'd like to be credited, but since the greater majority of my tiles are edits or rips, I wouldn't lose sleep over it. Like Geoffrey said, I just don't want people claiming it as their own. Unless it's terrible, then go ahead and claim it.