Most buttons have rounded borders with white background, they can't be used on pages with backgrounds other than white.
- make them transparent gifs without antialiasing
- supply us with more non-rounded images
- make the background color configurable
Additionally I would like to see some animated ones (gif or swf).
Stuff them with keywords: "free" (german: "kostenlos") and "download".
CTR is quite high for referrals but conversions are low.
I guess ppl are even downloading but then forget about it and don't install. Can't that be forced?