Has anyone made their own laundry detergent?

I've seen recipes before in magazines like "Natural Home" (a good magazine, by the way) but have all of my magazines packed away (we're just living in our current home for a few more months) and wondered if anyone could give me a recipe they've used and actually liked and that got their clothes clean.

What kind of fragrance can I add -- is it OK to mix in a little sauna scented oil or something? I'd like to do something less expensive and much more environmentally conscious than the stuff at the regular grocery store. I like the idea of Seventh Generation's detergent but it's kinda expensive, though I do realize it's very concentrated and would last much longer than regular "Tide" or whatever.

Just fishing for ideas, if you have any they'd be appreciated!