Everyone's favorite is ASICMiner, of course.
However, I think you completely missed some of the most interesting investments.
Check out:
BTCINVEST - Fund that targets BitCoin growth without Fiat exposure.
JAH - Mining Bond with daily dividend (straight Hashrate based)
RTM - Mining Bond with daily dividend (straight Hashrate based)
Cado.AvalonB3 - Mining Rigs with possible growth
Win.Avalon - Mining Rigs with possible growth
The trick is always how to value these investments. Think deeply, as you should with any mining investment.
Enjoy,
-MikeMark