I've used Mint, but sometimes I wonder if it isn't a great idea to put my financial data out on the "cloud."
So I've used GNUCash, which is a very nice, free and open source budgeting software that has been developed and maintained for many years.
http://www.gnucash.org
Definitely recommend checking it out.
They have versions for Windows, Linux, and Mac OS (both Intel and PowerPC).
I've used gnucash since 2003. It's my current finance app of choice. A few observations:
* I've used Money. It's slicker, but doesn't run on Linux (obviously). It lacks some geeky features (below).
* gnucash is probably the most accurate representation of accounting principles. This probably makes it a tad less easy to use, but (IMO) makes it more "correct".
* it'll run on Linux. For me this is huge as it means the only time I ever have to boot a windows machine is to do my taxes. (No, I don't wanna use a web based tax program.)
* It writes it's data in a non-proprietary format. (It is either xml or a mysql table). For lots of people, this falls into "who cares." For me, it's huge. I parse the xml file and generate reams and reams of data... predictions... graphs... etc. The output of this also gets automatically run through multiple scenarios of firecalc. I am a sucker for graphs. You can look at your stache and it looks a little flat... but you zoom out to 10 years worth of data and "holy crap! Look what I have done!"
If you just want accurate and free: this works.
If you're a geek and want to play with it.... you can do a lot.
By far, the most painful part of using gnucash was the transition: moving data out of money and into gnucash in a way that makes sense. It does import most of the standard formats... but mapping the Money categories into proper Income/Expense categories takes a bit of effort.