Here are some cool things I found out about resizing windows in osx lion.

• you can resize from any side or corner.
• hold alt and resize from a side and the opposite side moves too.
• hold alt and resize from a corner and all the corners move
• hold shift and resize from a side and the window resizes proportionally as if the opposite side is fixed
• hold shift and resize from a corner and the opposite corner is fixed
• hold alt + shift and resize from a side and it does the same as holding alt on a corner
• hold alt + shift and resize from a corner and the window resizes proportionally as if the center of the window is fixed