There have been many attempts to make avatars invisible in Second Life, and none of them have been very successful. An early method covered the whole avatar with an invisiprim. However, invisiprims leave a visible "signature" when they are viewed against any transparent or semi-transparent texture, creating a strange "outline" of the invisiprim.
Another method displaced the avatar under the ground. I remember chatting with one person who used this method, combined with a large flower. The end result was a five foot orchid with a name tag...very funny! This method had the serious drawback that the underground displacement was canceled when the avatar moved. Pop! Up he comes, and boop! down he goes, planted in a new location. It reminded me of a little kid, hiding behind the furniture and trying to sneak from the chair to the sofa.
With the introduction of alpha layers, true body invisibility became possible, without the limitations of invisiprims. But, like the previous methods, alpha layers still did not hide the avatar name tag. We all dismissed "invisibility" as a toy, because you could always see that telltale nametag floating in the air.
But the other day, my partner called my attention to a new item, a "Cloak of Invisibility". This item claimed to hide not only the avatar, but the nametag as well. Since I teach a class in Avatar Safety, I'm interested in any new development that could be misused by griefers and pranksters...so I bought a copy to see for myself.
A bit to my surprise, the damn thing worked as advertised. As soon as I put it on, I disappeared entirely, nametag and all. I could move about without becoming visible. This was a little bit disorienting, and I felt like I do when using a text only client. I was "in" Second Life, and yet...I was not.
The Cloak does have three limitations. If you have Voice enabled and are on Voice-enabled land, a white dot shows above your head to indicate your Voice-activated status, and anyone else with Voice can see this dot. The Cloak does not hide this dot, so you must disable Voice to be completely invisible. Second, you are still visible on the Map, the Minimap, and avatar radars as a green dot. And finally, even after you remove the Cloak, you must teleport to another region and back again, or re-log, to become visible again.
It's not a perfect solution...but it's a big improvement over previous methods, and unless you are being vigilant, it will be easy for someone wearing one to play tricks and practical jokes on you, or to lurk near you and eavesdrop on your chat and activities. Keep a sharp eye on your radar!
No, I'm not going to give you directions on where to buy this thing. Even though it's an impressive achievement, I cannot endorse a product that will surely be used more for harm than for fun.