From Anti Music.com (seriously, how much more can they dig up? Just do a new album for God's sake!):

Andy Partridge is asking fans what he should include on Bric-a-Brac Breakfast, a forthcoming companion to XTC’s 1990 odds-and-sods collection Rag & Bone Buffet: Rare Cuts & Leftovers, which itself is being prepped for a reissue this year on the bandleader’s Ape House Records.

Writing on Ape’s blog, Partridge says XTC is planning to reissue the 24-track Rag & Bone Buffet — which collected b-sides, BBC sessions and tracks by side projects The Three Wise Men and The Colonel — with “lots of new notes, photos and a sparkling remaster job.” Furthermore, “we also think there is a sister volume to be found. Yes, another herd of b-sides, extra tracks or odious oddities that found themselves escaped into the wider world and we’d like your help in rounding them up.”

To that end, Partridge is asking fans what “you would like brought back from the grave.” To be considered, the songs must not appear on Rag & Bone Buffet or be found “sitting snug on a regular album somewhere.” A few tracks already have been selected, including “Spiral” and “Say It” (the two new tracks included on 2005’s Apple Box), as well as “Where Did the Ordinary People Go?” (a digital-only single also released in 2005). Partridge also asks, “The 12-inch remix of ‘King for a Day,’ anyone?”

Submit your suggestions for Bric-a-Brac Breakfast in this thread on Ape’s forums.

If you haven't been following it, Andy (and sometimes others) have been participating in interviews about various songs throughout XTC's career.
They post on MySpace, but you can link thorough Chalkhills
http://chalkhills.org/articles/

When Andy Discusses a song, it is always great reading.

Yeah, it would be nice if they came out with some new material, but I know I'll be getting this.

To my knowledge, the Homo Safari series hasn't turned up anywhere else other than the two that were "Mummer" b-sides (and the CD single for "Dear God"). The first one is easily one of my favorite XTC songs.

Actually, I know of three 12-inch mixes of "King for a Day" but one would suffice.

Also, don't forget "Cherry In Your Tree" from a Where In The World Is Carmen Sandiego album.

Bingo! I have that CD... somewhere.

Andy also released a few songs on a CD as part of a CD subscription series. Can't remember the name of the series or the songs. Maybe someone can???

Sundodger, was that the series spearheaded by one of the guys from They Might Be Giants? I vaugely remember reading about it. I was tempted to subscribe but I never did. As I recall it was a series of ep's, each by a different artist.

I'd like to see the "Wonderfalls" TV theme song on there...

"Hello" selection...

http://chalkhills.org/reelbyreal/a_AHelloSelection.html

Looks like most songs have been released. Perhaps not these versions though.