I use a Vantec Aeroflow on one of mine. Bought it back in Feburary for about $25. It's pretty popular- very easy to install and came with a really nice smooth finish on it. No need to lap.
Otherwise I've got a SLK 947U (got it on sale for $20, but you still need a fan), one of those all copper thingies. Better cooler, but more work to install.
Mobile XP 2600+ (11X200)
Abit NF7-S v 2.0
Maxtor 60GB ATA 133 7200RPM
512MB Corsair Twinx 3200LL
BBA 9800 Pro
Enermax Noisetaker 420 watts
Win98SE