Find freeware versions of commercial apps with Last Freeware Version
There's even a web site dedicated to finding the last version of apps that you don't need to pay for. It's cleverly called Last Freeware Version. The site features brief descriptions of each application, a link to the product homepage so you can buy the full version or download a free trial if available, and a download link for the last freeware version of each app.
The user interface isn't that pretty, and there's no search feature. But you can always use Google to search for specific apps by restricting your search to