Duct tape and candles are excellent additions. I particularly like duct-tape as I'm too clumsy for knots and too poor for chains. And you can just cut it off with a bit of care and pair of scissors at the end. (If you've got the kind of sub who complains about having it pulled off, try soaking the taped part in some soapy water. But imho it's no worse than a particularly large band-aid)

If you're of a psychologically cruel bent, a leaky shower can make a servicable form of chinese water-torture apparatus.

In addition, I used to work in a pub (so it's not really around the house, but oh well) and when the beer taps got replaced, I nicked the handle off one of them. Remove the brand sign and you've got a very useful (if rather weighty) little dildo. Disinfect the handle first, of course.

Deep heat/icy hot/dencorub (depending on where one lives) can also be useful, if applied strategically. I've never tried it on female genitals as I'm not sure of the safety, but the soles of the feet, back of the neck, testicles and behind the ears are all excellent spots. Especially if you buy an extra strength formulation. Anyone with experience of using it on the clitoris/labia please contact me, I'd be interested in knowing how it worked and any tips you might have.

Otherwise, just take your partner and go shopping. Try a big hardware place or a department store and just let your imaginations run wild.