I came across this list of free and open source software packages from wikipedia. It is quite a comprehensive list that has categories such as Science, Theology,Networking and Games.
Before purchasing a software I will definitely take a look at this list. Two software I currently use from this list are RSS Bandit and KeePass.
RSS Bandit I tried it after my previous RSS reader crashed too many times. RSS bandit is written in .NET and it syncs my Google Reader Account
KeePass I find useful to store and encrypt my passwords. You have the option to install on your PC or have it on a flash drive.
Due to the economic climate of 2008, some companies started to look to open source in a effort to reduce IT cost. Why not you ?