Other folks posted much more clever and original ideas than mine here. But for a mug I would actually enjoy seeing on my desk daily…
--> Lift the rounded-corner blue bar off the top of the PostgreSQL.org web site:
http://www.postgresql.org/
and wrap around a white mug.
So, the left-handed see the elephant head and "PostgreSQL".
The right-handed see "The world's most advanced open source database.".
--Basil Bourque