As a service* to math students everywhere (especially those taking calculus), I started Mathematics.SE Index. The plan is to have a thematic catalog of common exercises in college-level mathematics, each linked to a solution posted on Math.SE.
As of now, the site has reasonably complete sections on Limits and Series, with a rudimentary section on binomial sums. All lists are automatically generated. Initial filtering was done with Data Explorer SQL query, using tags and keywords in question body. The query also took into account the view count (i.e., how often the problem is searched for), and the existence of upvoted answers.
The results of the query were processed with a Google Sheets script: a bunch of regular expressions extracted LaTeX markup with a desired pattern, checked its integrity [not of academic kind] and transformed into WordPress-compatible markup.
Plans for near future: integrals (especially improper), basic proofs by induction, , maybe some group theory and differential equations… depends on how easy it is to teach these topics to regular expressions.
(*) Or disservice, I wouldn’t know.