Ooh - can I throw out a few comments?
One the version of mine - you might want to increase the sizes of some of the fonts, as they're kinda unreadable. Also, the red and blue don't go well together. Make the border the same color as the font, in my opinion.
I like the version of Goss'... but one thing: the image sticks out the side. Also, the red doesn't ENTIRELY go with the picture. Try and pick one of the colors in the picture, so it all fits together.
The green/yellow one... the colors are a little too... vivid, in my opinion, so maybe pick toned down versions? Or maybe Dark and pale green (same shade), or dark green and black, or dark green and white. Also, the pink font/banner at the bottom do NOT fit in the slightest. Pink and green? *shudders*
Finally, for your last one... the colors don't really work. The yellows are again, a little too bright. I also don't like yellow, so I might be biased....
The pink font also does NOT fit. At all. The avatar and siggy at the bottom are pretty awkward too...
I made a version of that one, if you like it
Now I have completely transformed this boxcode into my own unique style. I still need to play around with making it prettier but now at least I have a more basic understanding of the core concepts.
I changed the colors, removed the bottom image (it didn't fit), and shrunk the width a bit... 800px is a little excessive, and sticks off some people's monitors