There are a couple of solutions.
1. Diatomaceous earth (DE) - fine sharp-edged remains of sea creatures. You spread the DE around your plants, garden, etc. The slugs live in the ground and under things that trap moisture. When they crawl out to get a snack, they have to crawl over the sharp-edged DE. They absolutely hate it.
2. Beer in shallow dish buried level in soil - slugs love beer except they drown when wallowing in it
3. Crushed egg shells - never have tried this, probably similar to DE
4. Hydrated lime - haven't tried this either probably very irratating to the slug.
If you have children, you can have them have fun (relative term OBTW) watching slugs melt!! Yes, watching slugs melt. Here's what you do. Give the children some salt shakers. Have them go slug hunting. When they find a slug, have them liberally apply a bunch of salt onto the slug and watch is melt away. The process is called diseccation. The slugs simplily kill themselves by expelling all of the moisture from their bodies to rid themselves of the salt.
Hope this helps.
Terry