I am primarily using Typo to write about a product I'm developing, and I find myself relinking to the product page and quite a few other pages very often. It would be great if Typo would automatically turn a word into a link if I'd previously linked that word, akin to how a wiki works except that it would just base the linking on what links I'd already used.

Obviously it would have to be tunable -- some links are transitory, but some links will be used many times. You would probably have to add some kind of link management facility, where you could specifically enable or disable autolinking a given word.