Here is some ideas and "preferences" of mine.

Different Mediums
First, think about how this will look on different mediums like t-shirts, business cards and in superbowl ads (kidding).  For example the winner of this logo competition submitted this alongside his entry so you can see exactly what his entry would look like on the different kinds of packages FreeBSD comes in.  The people who submit t-shirt art to Threadless do the same thing.  I really like this idea; if you can, try to put your logo on different printed materials. If you are looking for shirt models, we used this site, which is who we get our T-Shirt blanks from.  You can see our feeble efforts here

Color Schemes
Second, I'm probably going to completely dump this color scheme, so don't be afraid to suggest a new one.  I don't like the green I'm using for the text background because I think it is too dark and doesn't provide adequate contrast with the text.  

As far as colors, I am a fan of less saturated, earthy colors.  I think it gives a site an aire of sophistication.  It is critical that the logo will work in two or three solid colors.  If you look, the freebsd guy included artwork for black & white, greyscale, and a two color job.

Font Set
Make sure your font choice will not clash with san-serif'd fonts like verdana.

Misc
I really like that with the photographica logo, I can make the black "GRAPHICA" white for the t-shirts - it makes the logo more flexible when you can do that kind of stuff.  I also like that if I wanted, I can remove the film bars and just stick to the text.

For some inspiration, here are some  others.  Take a look at logos you like and think about why.  Don't be afraid to ask me what I like or what I'm going for :-)

Keep it up, and make sure to spread the word about this contest!