h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

I've got this beautiful conservatory built onto the back of my house. The only problem with it is that every morning I open the door to find a yucky slug trail over the carpet and anything else lying on the floor. And there's that horrible sickly sweet smell of slug slime.
Occasionally we discover a slug on the carpet and dispose of it, but usually there's no sign of the beggars.
They must be getting in somehow, but we can't work out how (or why-there's nothing they can nibble on, unless they like cacti!)
Any ideas on how to keep the little blighters out?

Sprinkle salt round the whole area, around the base of the conservatory wall. Doesn't do the soil any good unfortunately...or the slugs *evil smilie*
They used to get into the kitchen of my old house... I wasn't impressed to find that they'd crawled several feet across the room, up the side, into a draw and eaten my chocolate, and got out again in a night
Is there any ventilation holes at the bottom of the wall of the conservatory? Thats how they got into my house. Bear in mind that they can squeeze themselves through very small gaps.

Saucers of stale beer at soil level. They fall in and drown and you drop them onto the compost heap. Seems like a reasonably good death to me. Another evil smiley

I use the beer traps to good effect in my garden but stale beer isn't the sweetest of smells to have around a conservatory. Slugs don't like getting their soft bellies scratched so sprinkling sharp stuff like gravel or broken egg-shells around might also help.

I know it's been said before, but have you seen what salt does to slugs? Sprinkle on the salt and retreat to a minimum distance of 15m (not quite that impressive). Evil cackle, laugh, hack, splutter, etc.