Actually, NetMeeting isn't exactly considered "obsolete" by MS. It's still available for download, and comes pre-installed with XP. In fact, app sharing capabilities of both IM clients from MS utilizes the T.120 protocol provided directly from NetMeeting.
Intel's H.323 protocol (which is the A/V protocol used for NetMeeting) does not support multi-point A/V in and of itself. However, this protocol was widely adopted by many different "webphone" apps. CUSeeMe provides conferencing mirrors on their servers, which creates multi-point A/V conferences using the H.323 protocol. There are one or two other services, but I can't remember who they are now...however, have your credit card ready.
Another option is corporate based: if your company has Exchange Conferencing Server, multi-point A/V with NetMeeting works great. It's essentially a browser-based utility. Performance is surprising, considering all the A/V streams. Unfortunately, it's corporate-only...no 'net buddies allowed.