Cisco Memory.

Actually it is not on CCO due to potential legal issues (we list unapproved
as well as approved and that made our lawyers squeamish). However, you can
call the TAC and give them your info (router model, existing RAM) and they
can then look up the info on the internal TAC webserver and give you the
appropriate authorized list.

Before I was made painfully aware of the legal issues I posted the list to
inet-access if anyone wants to dig through the archives (it was only about
2 months ago).