bought a rooted phone

[Guest Koka_noodles]

I bought a second hand htc desire a few months ago and have only just noticed that it has been rooted. It's running MoDaCo custom ROM r9, android 2.2. Can anyone give me some hints on what this allows me to do? any must have apps? do rooted device apps appear on the marketplace? is there a better version I should brick my phone by incompetently trying to install? any hints or help would be super.