PyCharm is good for a 'heavyweight' IDE, and you can get it free if you're involved with education or open-source. TextWrangler looks like the best free option

PyCharm is good for a 'heavyweight' IDE, and you can get it free if you're involved with education or open-source. TextWrangler looks like the best free option to me, for those of us who lack the patience to learn emacs and vim. For java, there's a nice lightweight IDE called jGrasp, that's free. My favourites are Coda and TextMate though, because they've got the proper Mac sensibility going on. Ie. they're pretty, the menus/panels aren't overcrowded, but there's a lot of power tucked away if you care to become a power-user.