There are plenty of examples of online investment clubs and lots of information on how to run one. See www.betterinvesting.org for example.

However, there's one part of your post that concerns me. You anticipate members living in different regions of the world. If any of them are not US citizens, you will have problems keeping your books and filing your taxes. This is not something that you want to get involved with as the costs will likely far outstrip any gains from jointy investing. To my knowledge there is no investment club accounting software that can handle these issues adequately.

Ira