I make extra money through photography by developing personal relationships with potential clients, and using the internet as more of a portfolio guiding people rather than as a primary money maker buyby itself.
Most of my photography money comes from shooting events (weddings, etc), or from one-off gigs where people want something photographed more nicely than they can do themselves with a pocket camera. I make more in any individual session than in the combined 5 years I've had my site. These sessions tend to be very directed as well-- the client needs such and such specific thing photographed, and are willing to pay $x for it. We both know what we're getting in the end, and it's a much more guaranteed prospect. If you can get the work, of course. That's where the relationships come in, like photographing school plays or other things in your community and then letting people know where they can find your photos.
Your photos are quite good, and looking through them, I think that there's a lot I can learn from you. One thing I would suggest is to categorize your photos. That way, people who come to your site can look for particular things that interest them. People who are interested in plant macros may or may not be interested in graffiti or musical instruments. If you approach your site as one way to advertise yourself, and think like a potential client, you can arrange things to suit the kind of client you want to attract.