During Second Life's lifecycle, many "competitors" have emerged and have sunk back into oblivion (google's Lively anyone?).
One of the more promising in my opinion, at least as far as intellectual property and "consumer rights" is concerned, was Metaplace. This was one of the only virtual worlds with a TOS that deviates from the LL-type coroporate style of "for any and no reason" and "all your base are belong to us":
