Here is a quick how-to for a strategy to prevent duplicate content across domains and subdomains of the same site by "whitelisting" discrete domains and redirecting all other requests to the main domain.
Google Page Speed Service is an interesting new offering for websites. It is currently free, but with limited availability for the time being. It claims up to 20 - 60% speed-up in overall page load. It accomplishes this by routing all site traffic through Google, which will automatically perform some optimizations such as minifying CSS and JavaScript and serving some page assets through its own content delivery network (CDN). This is quite interesting, and there is even a site that runs a test to show you how your site performance will change if you use the service. We ran this test on a few client sites, and certainly there was up to a 25% performance improvement on some; however, for others the Google-optimized version was slower!
Do you frequently use the Google, Wikipedia, and other search boxes in Firefox, typically in the top right of the window? Ever wanted to add your own for a site that isn't on the directory? Here's a quick and dirty guide to creating your own Firefox search engine plugin, using the api.jquery.com search as an example.