The list of courses available this year is linked from http://www.inf.ed.ac.uk/teaching/courses/. To see which courses are normally taken in the third year, click on Normal Year Taken to sort by that field, and scroll down to the relevant section.
Clicking on the name of a course takes you to the official up-to-date Course Descriptor for that course, and from there you can normally click to a home page for the course. This is where the lecturer will place copies of slides, coursework, etc.
This year as in the past a Level 10 Advanced Databases course is available. Next year, however, this will be replaced by two courses in the area, one Level 11 (MSc) and one Level 9 (third year). Thus there is the possibility that this year's third year students miss out, since this year there isn't a L9 Advanced Databases course and next year there won't be a L10 Advanced Databases course. If you're interested in the area, though, you may take the fourth-year Advanced Databases course as part of your third year studies. Unlike other cases of taking Level 10 courses in third year, this does not require any special permission from Head of Teaching. See http://www.inf.ed.ac.uk/teaching/courses/adbs-4.html for details. You are welcome to attend the introductory talk on 20/9/06 at 10.00 in JCMB Room 3218.