Rubber stamps not on cling foam anymore?

You can use a repositionable glue directly on the rubber - Alene's Tack It Over and Over is good, and so is Tombow Mono Multi (white bottle with green caps). I've been using the Mono Multi because it's my go-to for most things that I use liquid glue for, so I usually have a bottle nearby. Just coat the back of the stamp with a THIN coat and let it dry, and it works just like the cling foam.

I know that there are other repositionable glues that people have used with good results; you can also use Scotch poster tape; I also remember there was someone who just swiped the back of the stamp with some lip balm. There's also a cling cushion that I can't remember the name of offhand, that you can apply to your block instead of the stamp. I prefer the repositionable glue because then the stamps will stick to my storage sheets as well as the blocks.

This is what I do. I unmounted at least 2,000 rubber stamps from their wood blocks before we moved from Virginia to Texas. I took them down to the bare rubber. I have no regrets.

I am also more than happy to buy stamps that are bare rubber, without any cling foam.

warrior1991 - Most of my background stamps still have the cushion on them; I never mounted them to the wood blocks in the first place and just coated the back with the repositionable glue. Sentiments, it depends. I've found that as a general rule, the smaller stamps actually stamp better without any kind of cushion. It's almost like the cushion makes them kind of unstable. If I have a set that comes with cling cushion on them, I don't take that off. It's only the stamps that I'm taking off wood blocks that I sometimes remove the cushion entirely, or stamps that I've purchased that are bare rubber (no cushion or cling) that I don't necessarily add cling cushion.

As far as if I decide to sell or give away a stamp/set? Hasn't happened yet. Having stamps off the wood blocks is a mixed blessing/curse. They don't take as much room to store, so there's less incentive to weed them out.

Microwaving can help; so can shoving them in the freezer for a bit. I liked the freezer better, because I could put a big bunch in there and take out one at a time to work on, while the rest stayed cold. I've used Un-Du on some that the microwave/freezer didn't work with. But once in a while you come across some that are held together with some kind of insane adhesive that was apparently developed for the aerospace industry and doesn't want to let loose for anything. And unfortunately, the only way to find out that you're dealing with this demon adhesive is when the foam comes off in chunks, so now you can't just say "oh, I'll leave the foam on this one". Those required scraping with some kind of plastic scraper and then rubbing at the remnants with my thumbs. 

Thank heavens I didn't have many of those.

If, by chance, you have any old TAC sets, with red rubber cushion - don't take those off the cushion unless you absolutely have to! The adhesive on those  is some of the stickiest stuff I've ever seen and it has reinforcing threads in it (almost like the sticky side of duct tape). Un-Du works on those, but you end up with a heck of a mess in the end; sticky stuff and sticky threads all over the place, and it's a challenge to keep it from transferring onto the working side of the stamp. Learn from my mistakes  

I took all of mine down to the bare rubber. I keep my stamps. All of them. Having them down to the rubber makes them easy to store and to find, even though I have more than I am willing to admit here. I keep them in the old PSBs. I can look through my entire, huge collection very quickly. I store certain types together (such as fall & Halloween in one binder, Christmas in another, florals in one, etc.). That helps.

Sometimes for 15-20 minutes, sometimes overnight if I got caught up in another project and forget I was working on them. I did put them in plastic bags, figuring that would keep the rubber from the drying effects of whatever keeps the freezer frost-free.

Everything that Scrapnana just said; also, an old-style pink eraser worked on a lot of mine (coupled with the elbow grease). Some of them worked by dabbing at it with packing tape (using sticky to remove sticky). And some I just rubbed at with my thumb to get the adhesive to roll up. Ended up with a really sore thumb, though, so I don't recommend that route.

Also tried a plastic scraper (like you can get from Pampered Chef to clean their pizza stones) and that helped when I coupled it with Un-Du.

I don't have all of mine down to bare rubber - some are on ez-mount. If I had one that the adhesive would.not.budge, I just put the EZ Mount over it. Hid the ugly and the stamp worked fine afterward.

Also, after the glue dries, stick the stamps to your arm or your jeans to reduce the gription a bit. They will still cling to your blocks for a good long time, but won't stick quite so aggressively to your storage board.