The only thing I love more than discovering cool new Mac apps is getting them at a discount.
If you scroll down on the right hand side of this page you'll find a link to the best way to do that: MacZot. Every day you get an offer for a new Mac app in your inbox. It's addictive and inexpensive... a great combo.
Another way to find great apps is through bundle offers, and there's a really good one going on right now. Go to Give Good Food For Your Mac and find a lot of really useful apps on sale. The more you buy, the bigger your discount.
The only downside for me is that these apps are so good I already owned a lot of them!