I tried cold packs, and ammonia on my bee stings.  I agree that these
reduce the pain nicely, but I get a local swelling over a 3 to 4 inch
extent which takes nearly 2 days to peak; then it subsides pretty
quickly.
 
The most-recent sting (one data point only) I treated with a venom
extractor that simply uses vacuum to draw out some of the venom (and
assorted other fluids).  It looks like an oversize hypodermic syringe,
although depresing the plunger creates the suction.  I actually used
the snake-bite size of the device; I bought an insect-bite and -sting
kit too - which is smaller - but couldn't think where I'd stored it.
(I still can't remember!)  I don't remember who made them; I bought
them at REI (Recreational Equipment Inc.).
 
Result:  it drew only one small drop of slightly bloody fluid.  The
stinging sensation vanished at first, then returned at a much subdued
level; I don't know when it stopped because I forgot about it.  The
good news was that there was almost now swelling - you COULD find it,
but it was no bother.  So I think I will try this first for my next
sting.  (There's always a next sting, no?)  Two-plus days of swelling
is what bothered me most with the earlier stings.
 
This is obviously no answer to the more acute problems such as multiple
stings or hypersensitivity.
 
Dick