BuddyPress.org

These are all that I’m aware of:

Cometchat is working on a BuddyPress integration with friends support. It’s a paid script.

http://www.cometchat.com/

Bowob Chat works, but does not have a friend feature, also you might get the plugin author’s ads on your site. Free (w/ ads).

https://wordpress.org/extend/plugins/bowob/

Footerchat is another possibility, again, it has no friends support and you will get some ads occasionally. Free (w/ ads).

http://www.footerchat.com/

Webbychat is another. Has a basic free option, which only supports up to 10 users. Variable paid options are available. You’ll have to manually configure the script to work with BP.

http://webbychat.com