On my cycle back from the British Beer Festival (yes, a great time had by all - didn't quite find the Lonix meet but only heard about it an hr before and not the main reason, anyway, I digress), I made some notes about post/telephone boxes (including most of the postbox refs where possible. I've also happened around the same route since and finally got round to making the edits. I found a postbox without a ref - I kid you not! Corrected Rosenau Road->Crescent, different the other side of the junction; that had bugged me for a while. Added a pub and a church or two (Prince of Wales in particular, right on a not-amazingly-well-marked junction - very handy for locating yourself).

With phone-boxes, if they're all in a clump I've decided after checking existing tag use at http://etricceline.de/osm/Europe/En/tagname=value, that I would go with 'count=N' rather than anything else or put multiple nodes in at the same spot. I even have a few other telephone boxes (not on these trips but elsewhere SW London) that I've stopped to mark down the telephone number. Haven't come across any of those yet that I've seen, although it appears usage has been made of various phone number fields. I'm going with phone=+44-20-..... as per the general recommendation in the wiki.