I look around this site and I see a lot of RAM questions. (fight club reference, anyone?)
I think it would be a good idea for some of the people that have these laptops to post up a link to any aftermarket hardware that they've tried and whether it was compatible or not.
Reference 1(one): crucial.com - this site has a compatibility finder for nearly every make/model of computer/MOBO in existence right now. And Crucial is (IMHO) a very good brand to use.
That's all I have, but please continue to share your experiences with hardware upgrades and their compatibility with the g53 series laptops.