I use blowtorch...
A hand-held propane torch works great, though the boards may suffer "discoloration".
I put the board in a vise, heat up part of it enough to melt the solder, then bend the top
of the board back a bit towards the copper side and let go - that flips the loose parts off
and into a cardboard box positioned to catch them. Much faster than trying to take off
each part individually. For some valuable items like DIP14 ICs it works better to pull them
manually, but the torch allows you to heat all the pins simultaneously. I haven't found
a failure in a CMOS IC yet after being removed this way.