Theres a bit of a gotcha in flex if you are trying to get large, huge or massive text in your labels on flex 3. I thought it would have been as simple as specifying a large value in the css for the font but this does not work. I eventually found the answer on adobes developers forum (thanks bguijt)

In order to have larger text you just do this with your label tag.

This will give you 200 size text... just keep scaling until you have the size you require.