I have a road bike w/Ultegra STI shifters and recently put on a pair of clip-on aerobars (Easton Aeroforce Carbon, in case that makes any difference) for long rides and some triathlons in August. What I'd like to be able to do is retain my STI shifters while also adding shifters at the end of the aerobars.

I have a vague memory of seeing a product that allows this, but don't remember any details. Has anybody done this setup?