I am figuring that companies such as Google implement their databases mainly on RAM and is part of the reason for the search results being so fast. If they are not I am sure they are looking to do so in the future.

RAM is superfast and I prefer to use it over solid state technology anytime. Of course there is the risk of data-loss, but you take that same risk with a harddrive crashing (backup that data).

This article goes into detail showing you how to use RAM as SWAP and why you might consider doing so.