You can try crushed egg shells, spread them around your plants. You can also sink a small container into the ground and have the top level with the soil and add beer into it. They seem to like the beer and they drown. I remember as a kid we would pour salt on them to kill them.
Good Luck

Coffee grounds work well as a deterrent too.

Diatomaceous earth works great. We had a severe slug problem because of our high water table. The last two years of record rains didn't help much either. I sprinkled DE in the garden last year and it has helped tremendously! Get the garden kind, not the pool kind (which has been tumbled so it doesn't have the raw edges fatally ingested by slugs but harmless to mammals). It's a fine dust you sprinkle around your plants. As with any fine dust (organic or not) wear a mask so you don't breath it in.

Thanks for the good ideas!

Betty, do you reapply it after every rain? I'd like to try DE and see how it does at repelling the little buggers.

... and where do you buy it?

Keep in mind that DE kills good bugs (including honey bees) as well as pests.
I used DE on the leaves of my newly-purchased-and-planted eggplants, and the DE dehydrated the leaves to the detriment of the plants.

Used coffee grounds (UCGs) are good, as someone already said. Leftover brewed coffee on leaves and on ground repels slugs and supposedly kills small slugs.

Water, yeast, wheat flour made into a slurry and left in gallon jugs is a great trap. Slugs drown themselves in the liquid. Refresh after a few days. Once I added a little triple phosphate, which I hoped would be toxic to slugs; I couldn't find iron phosphate, so I used triple instead. No chemist me.....

Prepare the gallon jugs: Cut a milk gallon jug so you have a large opening for the slugs to enter and for you to stir the liquid. Leave enough of the plastic side to retain handle, so the trap is easy for you to carry and empty. I like the handle a lot! and the size of the gallon jar is great too. The small dishes that usually are recommended are too gross for me....

Thanks for the idea, ppod! I'm tired of making midnight runs to pick them off. It is mightily gross.

Do you bury the jug? Halfway or all the way to the rim?

Sorry, didn't get back to the site for so long....

I don't bury the jugs. Slugs spend lots of time creeping up the sides and then down on the inside, all the while not eating my greens. When on the inside, I may give them a helping hand dropping into the pool. W/o flippers, they don't swim too swiftly. Any slugs I see around under boards, on leaves, etc. get dropped into slurry as well.

When the slurry starts to reek and attract flies, the garden hose spray can sink a lot of flies. The containers get emptied in the woods, and immediately, mess on ground gets hosed down to avoid attracting vermin. Or the mess (of decaying slugs) can be buried in the ground.

I noticed that some (cucumber?) beetles had drowned themselves in the slurry. The beetles were black w/orange dots on their backs. Good-looking fellas, but I'm afraid, not good for the vegs. Bumblebees never go near the slurry, nor do bees or wasps.

After being emptied, you may find a thick layer of flour sticking to the container bottom. Great! I just add water, mix w/a piece of wood, and the trap is ready to go again.