Wallasaurus makes a good call on Notepad++, I use that at home since it's free. At work I've got Textpad, but I still use NP++ for nearly everything because I prefer its syntax highlighting (easier to manage). However Textpad's "find in files" is bloody good.
Regarding Filebox Extender - I used that for a while, but now and then it used to really weird out Photoshop. I think it was because of the little icons it attached onto the corners of windows for the favourites drop-downs. It would attach those onto PS document windows (completely unnecessary) and sometimes those document windows would entirely disappear until I alt-tabbed out of PS and back in again.
It never did that before I installed Filebox Extender, and the problem immediately went away when I uninstalled it, so for that reason I'm sticking with DirectFolders since it doesn't interfere with existing windows.
I use FileZilla at home for FTP, free and fast/easy. I know we used it at work for uploading builds too, and as far as I know it never had any issues.
On the art side, Meshlab is a great open-source tool for optimising multi-million-poly ZBrush or Mudbox meshes.
I think it's awesome that people have been able to create free or open-source software which is almost as powerful and full-featured as expensive consumer apps. Definitely helping to level the playing field, plus open-source stuff is handy if you need to adjust a tool to fit your pipeline better.