I have a couple of suggestions for the front page:
(1) The horizontal navigation bar is not needed, clutters the page too much, and forces the main navigation down.
(2) Pick a position for icon text and stick to it. Different text positions on different icons are not user-friendly (users generally expect the same type of information to be on the same position, not scattered).
(3) If possible, to make your own job easier, you should create the icons without text and then add the actual text into the webpage itself. It makes maintenance much easier.
(4) I would personally get rid of the descriptions below each category. All categories are self-explanatory, except for "Gamers" (which can be renamed "Seeking Gamers"). Descriptions can be displayed as tool tips (or you can make a side bar on the right side which would display the descriptions onMouseOver).
(5) onMouseOver background color does not provide enough contrast with the white text. If you get rid of the text, it's not such a big problem, but I personally prefer much subtler onMouseOver effects. For example:
http://www.asp.rs/nikola/enworld.html
(incidentally, you can view source in that page to see how to set up a css class to handle your background-changing and such; I'm using a 2x2 px image with 2 solid and 2 transparent pixels myself, but I could have just as easily added borders to the cell...)