The twins have become hardcore They Might Be Giants fans.  Sure, their father is a big fan, but now they've become obsessive over John and John.  They're learning lots of TMBG songs, they can tell which John is singing any song, they're learning the clunky dance steps in the music videos, they're learning about melody, instruments, arrangements, song construction, lighting, stagecraft, and they're completely joyous over the music.

I *highly* recommend all the "TMBG Kids" stuff for young children, probably ages three and up:

"Bed, Bed, Bed" is a book of four illustrated stories and includes a CD with four matching songs.  It's very much in the style of quaint vintage children's books.  And it really is good for bedtime.

The CD "NO!" is halfway between a regular TMBG album and a children's album.  It's very good.  And it rocks, because kids like loud music also.

The DVD "Here Come the ABC's" was released very recently.  The presentation is similar to Sesame Street, music with cartoons and puppets, but there is also some footage of the Johns playing, which is great.  The edition that Amazon sells has some excellent additional material.  There's also a CD version.

And for slightly older children (mine are 4-1/2 and loving it!) as well as regular adults:

The film "Gigantic (A Take of Two Johns)" has just been released on DVD.  It's a really fine documentary about the Johns, and includes several hours of additional material.  (Parents' note: there are a few swear words in a couple of the interviews.)  My favorite part is the live footage of "James K. Polk", the kids favorite part is the live footage of "Don't Let's Start".

For reference, here are the TMBG sites:

They Might Be Giants main site: http://www.theymightbegiants.com
Giant Kids: http://www.giantkid.net
TMBG fun site: http://www.tmbg.com
Dial a Song: http://www.dialasong.com
This Might Be a Wiki TMBG Encyclopedia: http://www.tmbw.net

So... right now, my kids' favorite music is by They Might Be Giants, The Beatles, John Coltrane and Dizzy Gillespie.  I'd say my work here is done.