Emule

[max0d]

I'd agree that emule plus is the better choice. The way files are uploaded is also different from emule. However, beware of version 1f (the newsest i think) as it appeared really buggy when i tried it. It kept crashing, using more upload bandwidth then i set it to, and every time i restrarted it it told me that the majority of my .part files were corrupted. I know you can use donkey doctor to repair them but its a hassle. Switched back to version 1e and had no problems at all.

[Vargas]

personally i prefer Tarod's mod:
ed2k://|file|eMule0.25b-Tarod.16d-binaries.rar|790523|6d93011f922e40845a26a7e9a68c0288|/
it uses less CPU, and has nice features, too bad he doesn't code mods anymore
BTW there are 1.1 million users on ed2k right now