tumblr is a great blogging system. But one of the key features it is missing is a way to back up your blog entries. The Tumblelog Backup Tool (http://boutofcontext.com/tumblr_backup.php) fixes this problem. On their site you point them to your blog, tell them the types of things you want to back up (entries, photos, songs, and whatever else) and they take care of the rest. They crawl your site and package it up into a single file that you can then use as a backup.