Capital Punishment

A lot of folks use uppercase text for titles. This is actually a sort of psychological holdover from the typewriter days. The only way to really make a title stand out in those days was to make it uppercase. Uppercase letters are often less attractive than lowercase and usually more difficult to read--not to mention the fact that Internet users in your audience will tend to think that you're shouting at them.
Try to avoid using all caps in your titles (or anywhere in your slides). Concentrate instead on choosing an attractive and easily readable font and font size.