This one might come in handy if you need a nostalgic moment, someone has created a site with old versions of well known and well used software (eg. now you can download Paint Shop Pro Version 1 if for some reason this was just your favorite). Actually I still use Paint Shop Pro 3.11 from time to time, it is so fast and easy to use if you just need to change a few pixels.
Go here for a browse down memory lane;
http://www.oldversion.com/