- Non-standard fonts (via sIFR, etc)
- Complicated animations
We're moving (quickly) towards openness on the web, but developers always have to cater to the lowest common denominator. Right now its IE6. Someday it could be Firefox. Standards take time to be supported by enough browsers with enough marketshare to be actually usable. It wasn't THAT long ago that CSS was weakly implemented by browsers that represented almost 90% of web market share.
Version 18.104.22.168 has lots of features but probably the most important one is stripping the evil DRM infection from Blu-Ray and restore your fair use rights.
The free upgrade can also remove region encoding, works on Windows XP-64 and Vista-64, and fixes a ton of bugs. You can get the update or a trial copy here."