Divvy is a very simple GUI based window manager.
Ranked in these QuestionsQuestion Ranking
Pro Requires virtually no configuration & is very easy to use
Divvy uses a drop and drag style UI that's simple to use and doesn't require any setup or configuration to get started.
Pro Reasonably configurable
You can change the grid dimensions and a very other visual settings to suit your needs.
Pro Has keyboard shortcuts
Although it's not in the same level as something like bug.n, Divvy does support the use of keyboard shortcuts to move windows about. You can even create custom shortcuts.