Adminer [http://www.adminer.org/en/] is a pretty sweet db administration tool. It's only one sub-300kB file with no installation or configuration (so if your hosting provider doesnt have any db tool you can upload yours in seconds), supports MySQL, SQLite, PostgreSQL and others, and does much more. I didn't had to use phpMyAdmin even once since I learned about this.

One "killer" feature for me: Adminer automatically links items in columns that have foreign keys set, so you can click on a value and it jumps to that item in linked table.