I'd really like to try my hand at portrait photography but don't want to shell out for the requisite lighting equipment... Is it worth-while to experiment with common household lighting? (Taking shades off of lamps, etc.) Or, will the results be so poor that it's not really practice...
Absolutely!
I'd suggest starting with window light and a reflector (a large piece of white board from the craft shop works, as does a silver sun reflector for cars.)
With household lamps you can go for the "bare bulb" effect, or use a desk lamp to get more directionality.
Then you can graduate to inexpensive hardware-store halogen work lamps (just don't use them with children or animals - these lights get VERY hot!)
The only thing to watch for is white balance - especially if you mix the lights. For example, window light will appear bluish while tungsten will be very orange-yellow; mix the two and it's a good candidate for conversion to black & white.

Thanks for the encouragement & tips... I'll see if I can get my wife to sit for me, though I'll probably have to promise not to post anything here... well, what she doesn't know won't hurt her!

make sure she doesn't have any spys on here =P
Cool.. let us know how you go! That's the beauty of digital - you can experiment and get results straight away. And what's more, you can photoshop the ones that don't turn out right!

Waste nothing =)
where in film we couldn't experiment and the crap ones were crap for ever, in digital you leae the good ones and photoshop the bad ones =)
That's true about film, Dewey - sadly true - but a great capture in film is a classic forever - when it's hot, it's better than digital by a mile - but there is no saving a miss - like you can in digital.