Basically, HTCSense.com allows users to manage their HTC cellphones from a computer. This includes managing contacts, saving all of your text messages, finding games and other mobile apps, and keeping track of where you go (i.e. restaurants, etc.).
Most importantly, HTCSense.com is a safeguard for that unfortunate occasion when one loses a cell phone. It will start by making the smartphone ring loudly (even if set to vibrate) and using the GPS function to locate the device on a map. Worse comes to worst, it will lock the handheld in question and erase all of your personal data.
All of this sounds incredibly useful. But unfortunately, only owners of the HTC Desire HD and Desire Z handsets can take part in all this, and neither of those are available in the United States just yet.