For the fan art, don't put the dimensions and size as the ALT text. Pretend that the ALT text will be read out in context with your page with a text-to-speech engine. If you can't think of something good to say, use alt="[image]", and put that other stuff in the title element. In most browsers that will come up as a tooltip.
Also please don't use target="_blank" (open in new window). It's really really annoying, and one of the most annoying "features" of HTML.
Your episode guides kinda spoil the episode, they give away the entire plot... and for the seasons that are incomplete you should add a note to that effect. Otherwise it looks like a bug.
For the starred ratings, make a nice star image with the alt of "*". It'll look nicer that way
Other than that, it's nice, the simple design seems to work well. Your site is nice, but I can see that when it gets big, it's static HTML nature will make it hard to maintain (but, you're on a freebie webhost). But if and when you reach that stage, you probably would have some sort of content management in place.
I admire you for making a site about a dead sci-fi TV series
, though.:P (This applies to all new sites)