We are looking to make a game like
www.runescape.com eventually, after a series of mini projects to get us settled with whatever language were going to use. Lingo is apparently a very powerful language, it is oo and has collision detection and many other 3d features under its belt. Im no expert but it does sound good...
Also, you can make shockwave games into downloadable .exe's that can play full screen so there is a lot you can do with it, then the overall file size wont matter really, i doubt it would ever get over 50mb.
Hopefully we will have a team of 5 people at the end of this, i know other people interested in helping with php for the site, and 3d modelling, just no programmers so we need to learn a language and i think our only two real options are Lingo or DarkBASIC Pro.