In the interest of "increasing the expert-appeal" of the site (@Evpok), and related to spirit of the answers to this question,
I would call for a universal guideline asking users NOT to to cite Wikipedia as a source when answering a question.
I hope that this site exhibits a professional, academic focus, and for that to be true, I think that
- there must be an assumed knowledge base in the field of linguistics for anyone asking or answering a question in the Linguistics SE.
- the community should prefer professional or academic sources over other alternatives.
Even though I know that there are lots of dedicated people that maintain Wikipedia (especially in the field of linguistics!), I have personally found it to be questionable on more than one occasion.
That being said, I can see how Wikipedia may be a jumping off point for a question, and I can see how it may be offered as getting-started reading for a related topic, so I am not proposing a ban on links to Wikipedia.
EDIT: Great places to find academic citations: JSTOR, LLBA, ASC and other journal archives (most of these require a subscription, usually through a school).
Lots of full-text journals are available online: The Linguistics Journal, Oxford's Applied Linguistics, Journal of English Linguistics, International Journal of Applied Linguistics, MIT's Computational Linguistics, Diachronica: International Journal for Historical Linguistics, Language, SIL ebooks, and many, many more.
Or, for primary sources: MIT's foreign language newspaper collection, SIL Language and Culture Documentation and Description; Corpora: UPenn's Linguistic Data Consortium, ICAME, collection of corpora, BYU's corpora list, Linguist List's list of corpora