Well, there used to be a feature reporting users and TB shared, but it was too inaccurate and expensive in terms of message traffic between nodes--space better served by searches and transfer. Check the network settings in Tools (part of the former display is still there). Better yet, click the spinning Lime to connect to the LW website, then click the hyperlinked "hosts online" in the upper right corner of LW's web pages to see the graph of user numbers. http://www.limewire.com/english/content/netsize.shtml is actually pretty interesting to follow.

As for anonymous p2p--it's still not widespread or mature enough yet. Google for ANTS or MUTE to find out more. The current thinking seems to be that a false sense of security is more dangerous. Being able to see IP's in the user interface is actually a very good thing IMHO, since anyone with a bit more than basic skills apparently can get that info anyway. It's good that us regular joes get to realize that our IP is easily visible on the net anyway. Proxies can somewhat hide your IP, but are often slow and only as trustworthy as the proxy.

As for freeloaders (leechers), I just let 'em be: it's just a stage and after a while users grow out of it.
IIRC, the freeloader controls have been ineffective for a while, and I suspect freeloaders are depreceated in other ways. No big deal--eventually all those downloads, if valuable, will find their way back into circulation on way or another.

So, share openly, and find the quality stuff you aren't ashamed to share. If that means "Britney" and the like get ignored--good.