I’m really pleased this "OT" hasn’t been reaped for obvious reasons.
I found some old favourites of mine here already and some great new ones.
Some of the old applications such as PFE32 can give the new text editors a run for their money. If you have a personal favourite I'm sure others in the Monastery would be interested to hear about it.
There must be hundreds of other gems lying on taskbars or hidden away, share them!.

Some of my FREE favourites

WordWeb, English dictionary and thesaurus sits on the taskbar very handy for synonyms.

Filezilla , Drag and Drop FTP and SFTP client.

PFE32 , Small text editor which carries line numbers and is small enough to fit on a floppy.

VLC Media Player , Fast media client that seems to open files that others can’t.

SnagIt , Screen capture and editing software, good for capturing small sections of the screen, and transferring to a document, also good for video capture. Now in version 8 + but this version is free.