The <tt>, <i>, <b>, <big>, and <small> tags are all font-style tags. Font-style tags are defined in HTML4, but it is strongly recommended to use CSS styling instead.
You should set your menu inside <ul><li></li></ul> tags.
Setting a pid of padding in your elements would make the content easier to read and lighten the overall design.
Deciding for a color scheme would make it more comprehensive.
Even borders (top is thicker than bottom on some blocks).
A nice font type would bring alot.
Right borders do not align.
The bottom borders of the 2 bottom blocks do not align.
Sponsors have no title. (not shure they will appreciate)
Background image (awfull quality lol) does not fit screen width on 16/9 format.
onHover animation on your anchors in the left menu would be a +.
Finally, I would bring a touch of jQuery on the pictures with the colorbox plugin, so that visitors may see them in big format.
Hope this will help ;-)