I'm looking into making a martini glass cake - not a sheet cake cut into a glass shape or sugarpaste glass. I need it to be a standing glass. I'm thinking about making the stem from rice krispies but maybe the top would be too heavy? Anybody have any ideas they could share? Thanks!

here is a cake in teh shape of a margarita glass someone did ... this may give you some ideas/help

http://www.cakecentral.com/cake-photo_796.html

Wilton makes a cake stand with a center post and plates, all in a kind of tower. If you use parts of it - 2 equal or close-sized plates, one upside down for the base and one right side up for the "glass" I bet you could make a stable standing Martini glass. The whole thing screws together. You could put a cake slightly larger than the plate on the top plate, trim the sides at a slight angle (like a topsy turvy cake)and then cover the stand with RKT (angling the RKT down the center post to create the V-shape of the "glass") and then cover the whole thing with fondant. It would need some kind of weight secured to the underside of the base to make it less-tippable. (Is that a word?) +
I see in my mind how I'd do it, but I am not explaining it very well. Does this make any sense at all?

My local Wilton supplier sells individual parts for the stand (kinda expensive) and I have seen used stands on eBay (lots cheaper) so I bet you might find one if you look. If you have a Wilton supplier, maybe you can look at the stand there. Here's a picture of the stand.
http://www.wilton.com/store/site/product.cfm?id=3E30BB93-475A-BAC0-52555DC793C1FEC1&fid=3E33109F-475A-BAC0-514197B5E889D67F