[handyman5]

With BetterTouchTool[1] you can both move and resize by combining keypresses with mouse movement; for example, I have it set so that holding Option will move a window along with my mouse cursor, and Option+Shift will likewise resize a window. No dragging needed, actually. It has a metric ton of other features, but these are the only ones I use.

Also, Spectacle[2] gives you most of the benefits of a tiling window manager without actually having to run one. I have Command+Option+{Left,Right} set to move and resize a window to the left or right vertical halves of my screen, and I use those combinations constantly.

Further, I second the sibling's recommendation for Witch. If buying a license hadn't removed the "You have used this X times" counter, I'd tell you how many times I've used it, but it's easily in the hundreds of thousands.

[1]: http://www.bettertouchtool.net/ [2]: http://spectacleapp.com/