Sphider is a lightweight web spider and search engine written in PHP, using MySQL as its back end database. It is a great tool for adding search functionality to your web site or building your custom search engine. Sphider is small, easy to set up and modify, and is used in thousands of websites across the world.

Lifehacker has a good article on how you can have texts sent to your Google Voice account get sent to your IM client. Pretty cool.