Thank you for the quick and very interesting designs! A few comments from me on these:
* Really like #3 * Also like #4 and #1 with the stylized "tt" * I like what I think you were going for with #5 with the "tt" that takes the shape of the eye, but it looks a little similar to me to the logo of another organization the US and I would want to avoid confusion * I less liked 6, 7, 8, and 9, as they evoked for me less of the "TT" notion * I didn't like the upside down T in #2 as much as the others.