One joy of the internet is that, no matter how narrow your niche, you can surely find blogs to support it, comics to self-parody it, and communities to squabble about it. These examples crossed my desk (er, desktop) this morning:
(1) For philosophy nerds: Advanced Dungeons & Discourse
The rewarding Mind Hacks blog highlights this philosophy-themed D&D role-playing quest.
And there’s the original Dungeons & Discourse, also by Dresden Codak. (The 8th-level positivist is immune to metaphysics, but has low charisma.)
(2) For language nerds: worst pun ever, with analysis
My own favorite guilty nerdly pleasure, Language Log, reports this appalling pun (an 18-second video). The pun is ‘good’, but it’s the comments below that got my attention, rife with linguistic-style categorization-squabbles, with duly-offered comparables and counterexamples. (That said, Karen is right: it’s not a mondegreen; it’s not like “Mots d’Heures: Gousses, Rames.” And I’m always happy to see a Hendrix reference in any thread.)
Of course, I can’t mention nerdly humor without this modern classic:
(3) For comp-sci/math nerds: XKCD
If you’re this kind of nerd, and you didn’t yet know about XKCD, well, then, you’re welcome. This recent favorite captures the full XKCD mandate of “romance, sarcasm, math, and language.”
The culture of the XKCD forums (excuse me: fora) are worthy of their own examination. Later. The various emergent behaviors include a variety of forum games.
Dan Scherlis 
If I understood half of what you’re talking about, I’d probably agree
Um? Thanks?
But please don’t think that *I* followed, say, the majority of the philosophy jokes in that webcomic. I’m just enjoying that fact that any narrow nerdly group seems to have their webcomic, or their own most-beloved bits of humor, and their own characteristic ways of sharing them — or arguing about them.