Now hosted on WordPress
The current version of the catalog is at mathindex.wordpress.com
It has been expanded compared to the description below. Still under construction.
Original version of the post
Standard calculus exercises tend to be posted repeatedly, for various reasons. And although one might hope that each new iteration uncovers yet another aspect of the limit $$\lim_{x\to 0}\frac{x-\sin x}{x^3}$$ this is probably not the case.
So, I wonder if thematic catalogs of links to standard exercises could exist somewhere on the site (or elsewhere). If they were sufficiently visible, perhaps the questions would not be repeated as often. If nothing else, a glance at the list can suggest possible duplicates quicker than search.
Using the Data Explorer and a little script I produced a demo version of such a catalog, posted separately at http://meta.math.stackexchange.com/q/16717/. The questions are ordered by "arbitrary hotness points", equal to 20*(total score of answers) plus the number of views. The list is not exhaustive; I took the cream of the crop. Sadly, large number of formulas slows down browsers on less-powerful machines.
After seeing a very preliminary version of the catalog (only trigonometric limits included)... what do you think of its feasibility/usefulness?
Analysis of the attempt
Seeing the painfully slow page loads in the catalog, I think it is preferable to host it elsewhere, reworking it into something like $\pi$-base. (For those who don't know: it's the catalog of topological spaces where one selects the traits that the space should or should not have, and gets a list of such spaces.) E.g., one could check boxes for "limit with $\ln$ and $\cos$, without other trig functions, at $ 0$." (Conceivably, one can deal with integrals, series and products in similar fashion.)
Looks feasible, given a little development time. My approach was to grab the content of limits tag from Data Explorer and then search through it with regular expressions. For example, "limit involving sine function, at zero":
/\$[^\$=]*\\lim[^}]*0[^\$]*\\sin[^\$]*\$/
After the likely limits were extracted, I did basic markup checks like comparing the numbers of {
and }
; broken fragments were rejected.
The encouraging fact is that the catalog does not have to be very good to be an improvement on the current situation.