Like many web developers, I use MySQL constantly. Sure I can just use the command line, but it is faster to use some kind of graphical client with a decent UI. There are many out there, but my favorite for a while was MySQL's own MySQL Control Center (which has now been discontinued for a while). The replacement for Control Center is Administrator, and I am just not a big fan of it. I loved Control Center because it allowed query browsing and database management, and you'd be hard-pressed to find both features in Administrator which is why I don't like it as much. There are third-party alternatives as well, many of which are not free, which is a sticking point for me? Why, because I am cheap. I currently use (and love) SQLyog community edition (free and full-featured).
Oracle also has a SQL development client, called SQL Developer (oddly enough). They just upgraded it in fact. Now it does easy import and export data in many popular formats. Not retyping all that data, priceless. Oracle's client will manage MySQL, SQL, and Oracle databases, which is rare to find a free tool that handles all three.
I will stick to SQLyog for my database management needs however, since Oracle's java-based solution needs to be configured to work with MySQL's JDBC drivers apparently. Often I don't have the time to install third party drivers, and configure them, that is what a client should be responsible for. Ease of use, and dummy-proofing your app, even more priceless.