Some of you might already know about this, but it may be new to some of you so here it goes:
Toshl Finance is a personal finance tracking application (online + smart phone) that tracks your income, expenses and allows you to set budgets for specific tags.
It has a really neat interface, but what I love about it the most, and what I think Mustachians will like about it, is the fact that it encourages you to spend less. An added bonus is the "shame" you feel when you enter an expense that is embarrassing, but you know it must be tracked.
It is also a viable alternative to mint.com for us non-US (or Canada) users.
If you can't use (or are too paranoid to) mint I encourage you to give it a try!