I'm of mixed feelings on the capitalization. It really isn't an acronym, but it is called 'a word with no phonetic pronunciation'. Randall Munroe himself mixes 'XKCD' and 'xkcd' on the site.

I would, since it's a proper name, write it as 'Xkcd' normally if not 'XKCD'. 'Xkcd' is officially "frowned upon" according to the comic's author, though.

Mr. Munroe has an actual set of rules for writing it listed on the 'About' page for the comic. He says that 'xkcd' is generally preferred, and that 'XKCD' is an acceptable alternative in situations such as starting a sentence with the name. 'Xkcd' is frowned upon, it seems.

So I guess it should be 'xkcd' in this case, unless I was trying for extra formality or some such thing. My original draft of that node had it starting the sentence, so I'll take that excuse as to why it's capitalized. ;-)

The truth is, although I know it's not an acronym it still looks like one and people unfamiliar with the comic don't know that 'xkcd' is a coined word. It's also usually pronounced 'X-K-C-D' in conversation when I've heard it discussed. That it's a short domain name that was available in both the .com and .org TLDs is really the biggest factor in how it was named. That there's so much attention to how it is written is pretty much painting the bike shed. It's Randall's bike shed to paint, though, so since he provides me so many laughs I'll try to remember how he likes his comic named in print.