I have to agree with Shojayxt on these points. Coin anonymity is not valuable in a world of anonymizing wallets & automatic mixers where every coin will be anonymous. The benefit to going with DRK over BTC would be faster confirmation times and ease of use, etc. I can't comment on the security or utility of the Masternode system because I don't understand it but I am intrigued by its potential use (alluded to by some in this forum a few pages back) as the basis for some sort of anonymous, decentralized alternative internet. Does anyone have any insight as to whether this is potentially achievable or realistic. DRK seems to have a very passionate and involved community; it may be that the coin becomes the start of something that was not originally anticipated by its creators. Maybe, we'll all be going to .drk websites in the not-to-distant futures.
Any service could be rendered over the Darkcoin masternode network. It just depends on what people want and what is practical to implement. I doubt an alternative internet (something like TOR) will be done, but simple messaging systems and whatnot could be implemented.
Anonymity as you describe in the beginning of your post is all trust based at the moment, which is what Darkcoin is seeking to remedy. Not only that, most methods are downright sad, for instance SharedCoin by blockchain.info does a terrible job of obfuscating your identity.