Changing domains was a big decision. My biggest concern was being able to keep my user, RSS feed, and search engine traffic. Luckily, the power of the .htaccess file allowed me to do so:
Options +FollowSymLinks RewriteEngine on RewriteRule (.*) http://yournewdomain.com/$1 [R=301,L]
The above .htaccess file code, placed on the old domain, redirects the user to the same URL on the different domain.
Quick, easy, and functional.
I recently posted an awesome (if I may say so myself) CSS3 / MooTools tutorials called Create a Photo Stack Effect with Pure CSS Animations or MooTools. The post presented two ways, a pure CSS method or MooTools-powered class, to duplicate Google+'s elegant photo stack...
For maximum performance, we all know we must put our assets on CDN (another domain). Along with those assets are custom web fonts. Unfortunately custom web fonts via CDN (or any cross-domain font request) don't work in Firefox or Internet Explorer (correctly so, by spec) though...
As you should already know, the best visual features of a website are usually held within the most subtle of details. One simple trick that usually makes a big different is the use of opacity and fading. Another awesome MooTools functionality is...
One event that's always been lacking within the document is a signal for when the user is looking at a given tab, or another tab. When does the user switch off our site to look at something else? When do they come back?
One more note. I recommend keeping your old domain for at least a year. Make sure to give users and search engines time to update.