In Reply to: we thought about that too posted by RKMC on Thursday, 29. October 2009 at 10:11 Bali Time:
Try the old way...get a container such as a large metal milkshake making cup, boil some water put in the milkshake container and place bottle in the boiling water (it doesn't take long to heat up here in Bali).
Or as RKMC also suggested the electric bottle warmers are very portable and convenient compared to a microwave....The boiling water method can be used anywhere you go though.