If they didn't already come with the driver for your printer, you can find icc profiles for virtually all of the printers and papers HP, Canon, and Epson sell on their web sites. For each Canon printer I use regularly (Pro9000, ip8500, 6700d), there are profiles installed in my system for every paper type they sell, and for each quality setting I can apply in the dialogue box. I haven't counted, but it's roughly 40 or so profiles just for the three printers. Add the ones I've made myself, and it's an icc cornucopia! 🙂
If you're not using the HP, Canon, or Epson papers, it can be tricky to get good icc profiles. These days, many of the more popular third party paper companies, like Moab, offer them, but just for the more popular printers. If you can't find any you can locate several places online that'll create custom icc profiles for your paper and printer. In fact, and this is unsupported conjecture, I think Aperture 2 & Leopard require updated icc profiles due to changes in the print and color engines, so custom profiles are the way to go.