I think a great Foundry setting would be to take various missions that Archer and the crew of Enterprise conducted from T.V. series and turn them into playable missions.
Not only would we get to interact with era of Federation history along the timeline we would be able to build an independent timeline that branches from the main timeline through the many novels and comics that accompanied the series, which I feel was a mistake to be taken off of the air.
Although I did not watch many of the Enterprise shows, which I should catch up on this Winter, the ones that I did watch were very well written and acted out...especially along the lines of T'Pol.... One episode, Storm Front I and II would be especially awesome to interact with because you would get to dress up in 1940's style clothes and battle against the Nazi's and their alien sympathizers in order to restore the time line.
Star Trek Enterprise Foundry would definitely be worth the effort to create either by members of STO or as a persistent environment developed by Perfect World.
Porthos definitely gives a paw up for this happen.