As this thread comes up pretty often, i figured id add my 2c...
Ive used that "engine xtream degreaser" sold at supercheap etc for $2, and it basically turned out to be shit. I picked up a bottle of "kenco degreaser" for $20, and using it tonight, its like magic.
Spray it on, let it sit for for a minute or 2, and *all* u have to do, is basically wipe it off. Everything comes up as new...