I made homemade laundry detergent a while ago for several reasons: to both save money and try something out that was better for the environment. Everything I've read on the "green" websites use borax and washing soda, though I think your choice of soap will be the determining factor of how "green" (literally and figuratively) your detergent recipe is.
Anyway I didn't blog about it the first time because it didn't turn out as great as I thought it would. The texture was clumpy unlike the shown picture which made me mostly cross my fingers every time I dumped it into another load. And you bet your a** I was going to use it...I had three gallons of it. Luckily it mostly did the job. Tougher stains required a little additional help from a stain stick, so it's probably not the best solution for someone with kids, but our clothes were otherwise clean--but don't expect that "mountain fresh" smell. There will be no smell at all.
So I just made another batch today and I'm feeling more confident about the results this time around because Ryan finely shredded the soap in the grater (instead of slicing off strips with a knife) and I made sure the soap completely dissolved in the water by pretty much bringing it to a wee boil. Only tomorrow will really tell when it's had time to cool and gel up, but I was a little impatient last time. Fine shreds actually made this time go faster and I was done in about an hour.
Update: The detergent is VERY gelatinous and VERY smooth! No clumps!