Get the newer version 1.1 here.
I have created a version of my classifier for 23andMe/deCODEme genotype data that I talked about before. It calculates the probability that an individual is "Northwestern European", "Southeastern European", or "Ashkenazi Jewish".
You can download it here.
If you use it, feel free to leave a comment or send me an e-mail.
Comments from some users who tried it can also be found in this dna-forums thread (registration required).
(clarification, June 17): This is not an admixture test, but a "guess his/her origin out of these three groups" test, a classifier. Here is a way to look at it: the classifier compares these three events:
How likely is this genotype to be NW European?
How likely is this genotype to be SE European?
How likely is this genotype to be Ashkenazi Jewish?
An admixture test compares the likelihood of all possible events:
How likely is this genotype to be (x% NWE, y% SEE, z% AJ), for all x,y,z>0 such as x+y+z=100
Admixture analysis is a harder task than classification, because it looks at a much bigger realm of possibilities (all x,y,z combinations). That is why people have been getting generally accurate assessment of their main ancestry component from various testing services over the years, but sprinkled with widely varying and often puzzling estimates of minor admixture.