A controller in the Miami ARTCC wrote a webscript that uses the data from FAAO JO 7340.2 for this as well. The search feature can be found here: http://coderx.net/~coderx/ac_icao/index.php

I'm the controller   That's hosted on my personal box at home, so it should be up most of the time, but I'd say relying on it expressly might not be the best idea.  If anyone needs the database it's available in SQLite v3 format ( easily used in perl, php, or C ), or in a tab delimited format.  I'm currently working on the back end so I can easily modify the database, to add virtual airlines and such, they'll have a country of origin set as "Virtual".   I also have an aircraft designator database that covers appendix A, B and C of the 7110.65s  You can see that at this url: http://coderx.net/~coderx/ac_desig/  The database includes fixed wing, rotary, and experimental aircraft types.    I've been working with the ZMA IT( Larry Wimble ) and we're considering maybe making this part of some upcoming project at ZMA, but nothing concrete yet.

Hope it helps,
--Jason