I mentioned GW's Watcher in the Water before. For those who are unaware, the current model is the second version of the creature for the LOTR game. Originally, there were just six independent tentacles on 1" bases. Now it's the whole monster (head & all). The drawback to that, apart from the price, is the idea that the tentacles can't be positioned separately around the pool.
The old version:
The new one:
GW can suck it, re: images on the page.
I found a "tentacles-only" set on eBay. Hopefully I'll win that auction. However, I did see an interesting scratchbuilt version online over at The One Ring. You can see the image over at the member's photobucket page.
I don't know about you, but I think that's pretty darned impressive. It's inspired me to make an attempt at modelling a head for the beasty. Time to break out the Sculpey!