Mac OS X has buckets of really neat features, many of which aren't always obvious. One of the things I use frequently in OS X is the "Recent Items" menu, which is invoked from the Apple menu. It shows recently used apps and documents.
Blast (US$9.95 for a single user) is kind of Recent Items on steroids. It resides on the menu bar, and keeps track of every item that was recently used or changed. Take an incoming download, for example. Sure, I can go to my download folder, but I often have more than a hundred items in there. Yes, I can then search by date and come up with it, but with Blast, it's instantly found with a click. That's something the Apple Recent Items menu doesn't do.
Even better, I can then drag the item somewhere else, like to an email, or to a program icon to launch it. Of course, I can double click on the item, too. All your recent saves are there, along with a list, for example, of what documents you read yesterday. If you have a favorite place you go, like a folder of images, that folder can be pinned to a sidebar so it is always there.