First there's "Birthday Card at Christmas," which Ian Anderson wrote for his daughter, whose birthday is in late December:
They did some fun takes on traditional Christmas carols, including "Holly Herald," which mixes a few different ones together, a variation on "We Three Kings" called "We Five Kings," and a take on "God Rest Ye Merry Gentlemen" that sounds like it came from the soundtrack of a film from 1952.....
The aforementioned nifty new arrangement of Bach's "Bourée":
They also did a new arrangement of Gabriel Fauré's "Pavane," which debuted on this album, and it also became a regular part of their live set. My favorite, though, is the versions Ian Anderson has done while accompanied by an orchestra. Here's one from 2005:
Finally one that this New Yorker likes a bunch, "First Snow on Brooklyn," which actually evokes that NYC borough pretty decently for something written by a guy from Blackpool: