Tagamac

PackRat, a desktop client for 37signals’ Backpack, is on sale for 40% off today August 7th, 2007 only, available through the MacUpdate promo.

I have never used PackRat or Backpack, and thus can’t recommend either one. However, 37signals has an excellent reputation when it comes to web apps and I’ve heard good things about Backpack, which is essentially an online area for you to store notes, links, to-do lists, and more. Both Backpack and PackRat support tags for your notes, although the tags are basically just glorified categories. May be worthwhile, may be not. I leave it to your discretion.