The Reasonable Transit Page has been discussing the Downeaster in a NSRL world and/or extending Acela/Northeast Regional service to Woburn. I've crossed into "Crazy" territory, so I'm posting here.
Semi-Crazy Transit Pitch
With the North-South Rail Link built, extend some Downeaster runs to Springfield via Boston and Worcester: (Brunswick, Freeport, Portland, Saco, Wells, Dover, Durham, Exeter, Haverhill, Anderson/Woburn, North Station, South Station, Back Bay, Lansdowne, Framingham, Worcester, Springfield)
Extend some other Downeaster runs to Providence via Boston: (Brunswick, Freeport, Portland, Saco, Wells, Dover, Durham, Exeter, Haverhill, Anderson/Woburn, North Station, South Station, Back Bay, Route 128, Mansfield, Providence)
This would give Portland a one-seat to Boston, Providence, Springfield and Worcester. Also, it would give Portland a lot of good two-seat ride options with frequent transfers: Acela/Avelia, Northeast Regional, MBTA Commuter Rail, Hartford Line, etc
Crazy Transit Pitch
With a new NEC alignment between Hartford and Providence, extend some other Downeaster runs to Hartford via Boston and Providence: (Brunswick, Freeport, Portland, Saco, Wells, Dover, Durham, Exeter, Haverhill, Anderson/Woburn, North Station, South Station, Back Bay, Route 128, Mansfield, Providence, UConn, Hartford)