I'm sitting here at work this morning and need to get some drawing files from a general contractor so I fire up my copy of FTP Explorer. Which, sadly, was once free and is now shareware with a $35 tag associated with it. But I did get it when it was free and that was ten year ago now and I still use the program on a regular basis. It's a thousand times better than the crappy FTP client through Internet Explorer.
Speaking of IE, I never could get Flash to work properly on it at work and about half the vendor sites I go to use Flash so I downloaded Firefox. Flash works fine on it and Firefox is now my default browser for both work and home.
So now my plans are downloaded but the image viewing/printing software we have here is one of the most God awful programs I've ever worked with. Which is why I view & print plans now in about 1/3rd of the time using the free IrfanView.
What free programs do you use that you couldn't (happily) live without? By "free", I mean legally available without cost and not "I got Photoshop for free off of Bit Torrent!". I also realize that not every program which is "free" is free for commercial use but we'll overlook that.