With the release of the new iMac models, Apple is clearing out the 'old' models. If you're looking for a deal on an iMac, they don't come by often...and the deals don't last long. There's a very limited number of them left:

$100 off - iMac (20LCD/2.4GHZ/1GB/250GB/SD) $1199 (in stock)
$250 off -iMac (24LCD/2.8GHZ/2GB/320GB/SD) $1649 (in stock)