After battling slugs for many years, though I have not won all the battles, I feel that I have certainly won the war. The ultimate solution is hand picking. For every one that you remove from your garden today, you eliminate the need to remove 20 or more of their progeny in the next few months. After three short years of conscientious effort, the population of birds that you nurture on your property will be hard pressed to find many slugs or snails.
Tools needed: At first you will need a flashlight, an empty coffee can, and a few short lengths of lumber or stepping stones.
Hand pick in the evening, dropping the critters into about 2 inches of water in the can. During the day, turn over the boards or stepping stones, which function as traps, and dispose of the slugs in similar fashion. That means, that twice per day, you need to spend just a few minutes policing your property. Before each episode, empty the can of drowned slugs onto your compost pile, and refill the can with 2 inches of water. In the event that your slugs turn out to be excellent swimmers, a teaspoon of salt or liquid soap or vinegar or household ammonia added to the water will induce permanent sluggishness. Note that slugs do not regenerate from each half when cut through. That is worth remembering when you encounter the adults while doing other chores; just snip them, stomp them, smash them; anything to separate head from tail.
After the first year, you can probably dispense with the flashlight and the evening hunt. Simply collect the slugs from your traps every morning. Relocate the traps from time to time or when the collection becomes sparse. That's all there is to it in most areas. My raised beds are composed entirely of soil derived from composting xmas trees. I have never seen a slug on these beds and do not place traps there any more. A good mulch can deter slugs. An exception occurs in the Pacific Northwest which has populations of giant slugs that travel long distances, so good control takes more vigilance and longer time. Techniques described here work well in my Midwestern vegetable garden. My ornamental gardens require no controls for this pest.
There are many other methods of control which require less "hands on" involvement, but they are much less effective, and will attract other critters in some cases. A complete list of these anecdotal methods can be found in the Slug and Snail FAQ http://homepage.powerup.com.au/~swimskins/slug_snail_FAQ.html maintained by Margaret Van Emmerik. If that link no longer works, do a search on Ms. Emmerik's name. I do not have snails, but include them in the title so that the reader with snail problems will find this link to the snail FAQ. Happy hunting!