We've said it many times before, and I'll say it again: one of the best things about Android is how customizable the entire experience is. One of the easiest and most comprehensive ways to customize your device - aside from rooting and ROMing, that is - is to use a custom launcher such as ADWLauncher EX, GO Launcher EX, and Launcher Pro. Even stock, these apps can revamp your device's appearance and basic behavior, and coupled with the bevy of themes that can be found on the Market, the possibilities are nearly endless.
So, are you using, or have you previously used, a custom launcher? Please note when voting: if you're running a custom ROM but using that ROMs stock launcher, please vote "no." Only vote "yes" if you have a third-party launcher installed and in use.