To quote a colleague, "Free is Good!", and I have always been one to seek out quality freeware and shareware alternatives to commercial software. In the Information Technology courses I have taught in the past, my students always were in awe of the great programs we could find, just by using some good search terms, or by using a couple of great online directories.
I thought I would share my list, because keeping it in my brain just hurts too much:
Alternative To - I think their about page says it better than I can: Tell us what application you want to replace and we give you suggestions on great alternatives! Instead of listing thousands of more or less crappy applications in a category, we make each application into a category. Think of it like forever evolving blog posts about good alternatives to the software that you're not satisfied with.
File Hippo - Anytime someone asks me about downloading a piece of software, this is the first place I point them to. File Hippo is a magnificent repository of all the software you need to make your computer happy. It's all in one place and kept updated.
Let me put it this way, have you ever tried to find the JAVA plug-in on Sun's website? How about the Flash plug-in for IE, no wait Firefox... er.. Safari. If you know what I am talking about, then you need File Hippo. It's all in one place, without having to click about 4 times to get to the right page.
The third one I use all the time is OSAlt. This is another great directory of alternatives to commercial software, and I highly recommend you stick it in your bookmark list.