The new attachment would be a net launcher, and since I noticed the L-TAG doesn't have any attachments, I think it would be a perfect fit (though other guns have launcher attachments aswell, I just wanted to give the L-TAG some attention too!)! The net would "deploy" after it was fired and it would entangle an area of X meters depending on where it lands. The effect would be almost like the flashbang grenade, but no blinding, just criss-cross.
I think this would be a fun addition to game play in future games. I think games should implement every opportune figure, so they are increasingly versatile- and Crysis has always done that. Also, nets have been used in warfare/hunting for thousands of years, just thought I'd throw that out there, heh.