I've read that good website layouts evolve slowly over time, and it's better to change and improve the layout you've already got rather than redo the whole thing from scratch. Probably sage advice. I tweaked my layout a bit to take more advantage of a bunch of empty space where nothing much was happening, and also to add more cow. My girlfriend drew me a cow silhouette for my blog layout. (By the way, when your girlfriend is willing to take the time to draw you a cow graphic for your blog layout, you know it's true love. <3) I used a sort of cliche'ed "reflective" effect, thanks to the GIMP, but such is life. I couldn't think of anything better to put up there, and this may be the first time it's ever been used on a purple cow, so maybe I'm breaking new ground.
I think there is a science to certain aspects of layout design. For example should you have your links underlined or not? It's likely that many people (especially people who've been using the internet for a long time) associate underlined text in webpages with links. Having links that aren't underlined may slip people's notice; on the other hand, having text underlined that isn't a link may make people click around on non-links before they notice. It may only break someone's concentration for a split second, but sometimes that can still be annoying, especially if it happens lots of times. To that end I try to make all my links underlined, and nothing else. An exception is that category cloud thing on the right, because I figure people are probably smart enough to figure out to click there, and the underlines cluttered it so much that it was hard to read. In reality I have no idea what I'm talking about, but these kind of things probably matter.
To my amazement, someone actually expressed interest in my putting this layout up for others to download, so I plan to once I remove all the places I've hard-coded the thing to work with my website. It's not the prettiest code in the world, but PHP never is.
I've said it many times, and I'll never stop saying it: you simple can't go wrong with cow-based web page layouts.