Undergravel jets are super nice for keeping detritus suspended in the water column and eliminating dead spots. I think Goofboy has a very nice how-to on UGJ system using a powerhead (
http://www.cichlid-forum.com/phpBB/viewtopic.php?t=208104&highlight=). Now there are some who will use the output from a canister filter to power their UGJ but if you're going to try the Goofboy method (or a version thereof) you're still going to want to have a HOB or canister filter there to filter the suspended detritus from your water column.
As an aside, if you're powering those UGJs with a powerhead, you'll want to make sure it has a reverse flow function, and that it has no problem operating 25" below the waterline.
Good Luck!