there's always a variable speed control fan, with manual control...turn it up for high-power apps, and turn it down at night (underclock it first) to quiet it down. really helpful for those who sleep in the same room as their pc and (still) haven't yet become used to the pleasant white noise of cooling fans whirring.
I just graduated from college, and left my girlfriend two states away (we still visit, don't you worry) and she complains she cannot sleep now unless there's some noise in the background.
I digress.
get yourself a fan which you can manually adjust; the automatic temp probe fans wind up and down often (imo) and are more annoying than fooling with the variable resistor manually.
happy computing!
~Branson