The National Museum of Computing, Bletchley Park, UK, has a decent
number in its collection.
There is also an active UK-based user group, HPCC (see
http://wwww.hpcc.org/ for details). We hold a meeting every monthh in
London (the next one is this coming Saturday), anyone here would be most
welcome to come as a guest (but please let a member of the committee know
if you want to come, for obvious security reasons).
This group officially covers all HP hadheld machiens from the HP35
onweards. In practic we talk about lots more, incluing HP desktop
calcualtors.
I should perhaps add that this group has nothign to do with the NMoC or
Bletchley Parkm and is not run or sponsored by HP.
-tony