How can I get a vanilla Android device? OK I'm about to buy an Android phone for development, but I will try to keep this question from becoming a shopping recommendation.

I want to have vanilla Android on my phone (i.e. not Sense or TouchWiz or something similar). Can I just buy a random phone and somehow revert it back to vanilla Android? Is there any risk of compatibility problems or hardware problems when doing that?

An easier option is to buy a phone that comes with vanilla Android, but the options are limited. As far as I know (i.e. not much), the only phones with pure Android are Nexus One, Nexus S, ADP and ADP2. Is that really it?
Yes, you should buy a Nexus One or a Nexus S. If you buy another phone like e.g. HTC Wildfire, you can't easily get the "vanilla" Android.