I've been using Eco Balls for about a month now. If you don't know, they're plastic balls that you use in place of detergent in your washing machine. They're good for about 1000 washes, so save you money as well as the planet.
Given I've done a fair bit of sweaty exercise, been to numerous smokey pubs and had the odd (ahem) unexplained stain, my laundry looks to be in remarkably good shape. The lady-cats in my life don't seem to recoiling in terror (any more than usual), so I think they're working pretty well.
There's no way I'd have ever bought these things off t'internet, except I got a recommendation from a bloke at work, who'd been using them for nearly a year. A look around the various places that talk about these things, the general consensus seems to be that they're good for most 'normal' washing, but keep some detergent handy for those special occasions.