I've been watching Pirates of the Burning Sea for a number of years. Over the years, it's grown a lot. For instance, originally it was going to be a ship-only game, like EVE.  In other words, you'd never appear in the game walking around like in most games.  You'd always be on your ship, doing things through an interface.  Eventually, they went away from that model and you can now explore towns on foot and such. 

It's got a lot of innovative features now, as well.

First, you can submit user content.  You can design you own flags and sail decals, and submit them for review.  If they pass a player and developer review, they'll be added to the game and you can use them on your ships!  Very cool!  For the most advanced digital artist, you can model your own ships!  You have to have a lot of historical backing, and almost all the submitted ships were modeled from actual period plans.  But for the advanced artist, this is an incredible opportunity!

Also, the entire economy is player-driven.  All ships, cannons, guns, everything, is made by players, and most of it is not permanent, that way there is demand for player artisans to replace aging and deteriorating equipment!  A great opportunity for those players that like crafting and want to be in demand.

This game keeps looking better and better every time I revisit the site.  I can't wait for a beta invite (hint hint), and of course for retail release (currently set for June 2007).