http://www.newegg.com/Product/Produc...82E16817121909
That's the hd cooler I got for the new drive. It's cheap and simple, and depending on your taste it looks either really good, or really bad.
I also replaced the oem case fan with an Antec Pro fan.
With both measures taken, the on-load temp has dropped on both drives significantly. The new drive has dropped from 38-40 C to 24 C, and the slave (which doesn't have its own cooler) from 42-44 to 34 C. Both are running nice and cool now...they're happy, and so am I.