The XIGMATEK HDT-S1283 is pretty legit and works well. Dropped my temps by 12-15c on a Q6600 G0 @ 3.6ghz.
http://www.newegg.com/Product/Product.aspx?Item=N82E16835233003
$36.99 + free shipping. Throw in some Arctic Silver 5 for $5.99 and you should be good to go.