I was looking to run Teamspeak Overay while running BFBC2 so I could "see" who was talking.
I used to use "Teamspeak overlay" years ago when playing BF2, so I found that there is a Overlay plugin for TS3 by the same bunch, but I couldn't get it to work for my machine (Win7 x64). A Check on the forums confirmed BFBC2 is NOT on the "working" list, although WOW and others do. Useful for some.
So, I hunted around and found "PlayClaw (http://www.playclaw.com/how-to-install-teamspeak3-overlay-plugin.php)" which is shareware. This works in the same way and also shows FPS, CPU temp & load and GPU details on-screen as well as TeamSpeak conversations.
I thought other players might want to know, or have suggestions of similar or better applications to do the same thing.