HTC's upcoming devices – the Touch Diamond2 and the Touch Pro2, will arrive, the way we got used to from the Diamond times, with a set of HTC custom ringtones and sounds for notifications.
You don't have to wait until one of these beauties comes out to give your device a sonic boost; you can now download and use the new sounds on your device, thanks to XDA Developers. You need to extract the sound files from the archive to Windows folder on your device (just skip files that are already there in case you run into that), then go to Start, Settings, Personal, Sounds & Notifications, Notifications and customize to your liking.