The Groups feature is a potentially powerful and useful thing, but right now it has some serious limitations which I know are being worked on. (Sorry If I'm covering already discussed stuff.)
We should certainly be able to be members of far more than 15 groups... however the categories of these groups need to be distinct so that they are used in different ways. Here are the following "types" or "uses" of groups we need to be able to set in some sort of Groups Configuration window or dialog box. (Honestly, I hope that some day the dialog boxes and the Inventory system can become a PDA or Laptop computer object that our avatar caries around.)
1) Groups intended for sending and recieving conversation from people connected to SL at the moment (I know, it's already implimented - I'm simply mentioning it as an example of a distinct use of a group membership)
2) Groups intended for messages that EVERYONE in the group sees, whether conected or not (these should go to a special INBOX, for group announcements. We should not have to use the voting feature for this as people do now. We should also have the option of being able to recieve messages of this type from a specific group even if we do not want to recieve other communications from Second Life externally - and these messages should be able to reach us as email or as SMS text messages on a cell phone or other device.)
3) Groups intended to give permission to a person to enter (or be blocked from) an entire sim, an area within a sim owned by a specific person (patch of land), or a specific area (like a building) inside a patch of land. This also means that sounds and cameras can be blocked for entering such an area or seeing from far away what is going on inside that area if the windows are blocked or one-way. (It should not be possible to spy on people with invisible cameras or with moving an avatar through a wall by moving an edited object through the wall while sittingon it - if the person who owns that area specifically has requested this not be possible or a program blocks this type of thing.)
4) Groups intended to give different levels of administrative control and building privileges in an area. This also means that the a number and type of things people can or cannot do as members of such group should be configurable on a person-by person basis as well as for the entire group.
5) Groups intended for fraternal membership in some assocation - like people who frequent a casino, members of an army, fans of someone or something, political activist groups, etc. (This generally is the group type which should be part of the option of having a name/label floating above your head. Other types of group are not neccesarily going to be used for such.)
6) Groups that allow a person to be affected (or not affected) by specific effects of specific scripts/programs, such as weapons or simulations of some kind (like illusions, hallucinations, dreams, time travel (in which past events from a specific location are replayed), visual tutorials and teaching guides (we might have some sort of visual 3D animation intended to teach someone how to do something, but it may be intended for only one person to visualize), etc.)
If anyone has other ideas for group types, please mention them in a followup message.