FireFox 3.1 alpha

FireFox has put out an alpha release of version 3.1.  Alpha means not ready for use for a majority of people; ok, that's not what it really means, but the point is the same; so it may be a while before these features are ready for use on sites.  But they look pretty slick.

Border Images - Let's you specify images to use for a element border rather than just a line width, pattern, and color.  Looks like it will make creating shadows and curved elements much easier.

CSS3 properties for word-wrap, :nth-child, text-shadow, box-shadow, and columns.  :nth-child is personally the one I think is going to be the best of the lot, or at least the one I use the most.  It will let you do CSS declarations like tr:nth-child(odd) to specify a style for odd rows in an HTML table.  No more looping in PHP to do the same thing once this property gets wide enough support.  Columns will be pretty slick as well.

Text support on the canvas object.  You'll probably just need to follow the link if you're not familiar with the idea of canvas.  Basically it lets you draw on the web page using JavaScript like it was a canvas.  Unfortunately, IE7 doesn't support the canvas object and Microsoft has stated that IE8 won't either so there's still a pretty significant roadblock there. 

And Safari and FF both are supporting web fonts in the 3.1 releases. For those that are tired of the web safe fonts, this could be a great thing.  You'll be able to host a TTF on your server and your visitors will use that font to view yor content.  Of course there are all sorts of licensing issues and some type of DRM will be implemented I'm sure.