[kaptain]

I recommend spectacle instead of divvy. There were a couple problems that I had with divvy resizing and placing windows. Spectacle addresses those concerns.

[8ig8]

I haven't used Spectacle, but I wanted to point out Better Touch Tool as another option to those investigating Window Mgmt apps/scripts:

http://blog.boastr.net/?page_id=1619

BTT provides the same window controls as Spectacle, configurable to your custom keyboard or mouse or touchpad actions, plus a lot more that may be useful to you. I've been very happy with BTT.

[Monkeyget]

I warmly recommend spectacle. Spectacle along with Alfred radically improved the way I interact with the Finder. Being able to summon files/applications/webpages/... and move the corresponding windows trough keyboard shortcuts alone is quite liberating.

[zimbatm]

http://spectacleapp.com/

[stelian]

I've added Spectacle to the post. It's pretty cool that it's open source.