To add some thrill in daily web-life I switched to beta channel of Firefox, and currently running on Firefox 7.0 beta 1:
Changes from 6.0 are almost unnoticeable. However I've so far I noticed that http/https protocol part is hidden in address input box. Questionable move since in our widescreen world saving some 20-pixels-wide horizontal space doesn't changes anything.Also I've noticed a hardware acceleration option in preferences, but as for now it's probably mostly a stub, by my guess.
Claimed memory usage improvement are not noticeble so far. Overwise beta runs pretty well, and I haven't got any even minor problems with it (not counting uncompatible plugins), so you can give it a try. Acid3 result is near to excellent, general performance is also quite good, so you can give it a try. As of now Firefox is still best browser in my opinion: highly configurable, yet with clean and simple structure.