Is there an official dialer code resource? There are a ton of XDA forums and a decent number of answers here that refer to specific dialer codes. For instance *#*#4636#*#* will cause unicorns to spring forth from your phone or tell you what OS you're running and how much RAM you have (I forget which). I found one list of Secret Star Codes but I'm wondering if there's a more complete list? Someone warned that some codes can really screw up your phone and it'd be nice to have a good place to point people for good information on what the codes actually mean.

Though in fact *#*#4636#*#*, which was recently recommended, is fairly safe, I think it is a good practice, especially since we all start talking about fire breathing dragons when the subject of rooting a device comes up, to make sure we're encouraging folks to make sure they know what a dialer code is going to do.
This thread over at XDA seems to be a pretty good start on this kind of resource.

Edit: I just noticed that the OP in that thread admitted that most of the codes listed wouldn't work in 2.2.  Bummer.

Edit 2: Found another one.  No indication of whether these codes have been tested and if so what device/ROM was used.