I might as well go ahead and post the icons that I use for my custom buttons in foobar. Adding buttons to the layout is easy and it is even possible to insert a second toolbar (e.g. over the playlist pane) but - without the nice icons all you'll be looking at is a bunch of unattractive question marks.
These icons have been extracted from the beautiful icon set led24 - check that out here!
All the custom icons above plus a few more can be downloaded here. (I may use this chance to recommend the open source zip utility 7-Zip)
I've created different kinds of star icons as well - for setting ratings. My original psd can be found here - it is sliced so png's can easily be exported and converted to ico using ConvertICO.com. However - I have of course already done this, which yielded these four variants (click image to download icons):
Oh, and of course you use the foo_playcount component for conveniently rating your songs in foobar.
Great... keep up the good work. Foobar2000 is THE best player around :-)
SvarSlet