I have been pondering recently whether it would be worthwhile for the
collective brains on u.t.l to put together an unofficial guide to
Oyster - with all the basic info that was previously in the booklet,
alongside the slightly more complex stuff that's not quite as widely
published, such as OSIs, split ticketing, and whether you can get
railcard-discounted PAYG capping when you're just travelling on buses.
Would anyone be interested in some kind of a web 2.0-type
collaboration?

I'd happily provide hosting for it and whatnot. I was going to FOI for
an updated OSI list in January to post on Reconnections anyway.