I stopped to look at my tag list on Stack Overflow today. Since Stack Overflow is a social network, the tags are a summary of the intersection of my interests with the interests of programmers at large.

That means computational linguistics does not figure highly in the list. AI only shows up twice. The number-one tag is functional programming. (I only list tags that occur more than once.)

functional-programming	12
scheme	11
lisp	11
haskell	6
python	5
f#	4
testing	2
programming-languages	2
emacs	2
common-lisp	2
c#	2
ai	2

So my useful expertise to the programming world at large is functional programming, and then a bunch of programming languages. Interesting.

Scheme/Lisp makes sense since there aren’t many people that know Scheme, but a surprising number of schools still use Scheme for functional programming courses. Also, there’s a continual stream of people discovering SICP and getting stuck on the exercises.

F# is a bit surprising, but I can answer F# questions because I (1) use Haskell (2) have used Caml and (3) have played with F#. F# knowledge kind of comes for free given Haskell experience and a little playing around with ML dialects, a lot like C# knowledge transferring to Java*, or Spanish knowledge to Catalan.

One positive thing about Stack Overflow is the way that its tags encourage development of communities. At least I think it’s positive—I’ve seen a couple of PHP and ActionScript questions show up tagged functional-programming, and the answers look like they come from a different world. Just as helpful, but with different grammatical and pragmatic standards. Fewer references to research papers and more references to “greetz".

One problem with communities is that members of smaller communities have a harder time earning badges. If you’re just after the badges, then your behaviour will be slightly different from the ideal, I think. But then this isn’t all that different from the XBox badges that inspired the Stack Overflow ones.

Edit: Linked to profile at the top of the page.