I'm going to add to this thread continually with UI changes that simply HAVE to be made. As we all know, the UI in LoL needs alot of work, lets give the dev's ideas one step at a time!
Suggestion #1: Combat Text
Look how easy this text is to read. The numbers are clearly visible, people spectating the game will KNOW exactly what is going on. This caters to the E-sport element of LoL. Spells cast upon the enemy are shown in YELLOW, and heals are shown in GREEN. Regular damage is shown in white. Notice how the numbers are kind of staggered. Straight numbers fading up are BORING. Have them randomize as they fade.