Despite having lots of school work to do, I have managed to create a new theme: Tetrad. The name comes from Color Scheme Designer, which I used to create a tetrad split of colors; the four colors are used on the four main sections of this site. I’ve tried viewing the site in Firefox 3 in OS X, Chrome in Windows, and IE 8 in Windows. The round corners look best in Firefox (they’re actually applied everywhere I specified! IE and Chrome slack off on this). Let me know if the theme looks awry in your particular browser, please. Other feedback and comments welcome, too. :)
If for some reason you’re not seeing the new theme, you can try explicitly choosing it. I’ve had trouble in the past such that I had to clear out a 3till7.net cookie from my browser before I could see a chosen theme on all pages. The old theme Block Pastel is still available if you prefer it. You can read more about all available themes (just these two right now), including credits, on the About page.