Can a dash work after a question mark?

Could you? Sure. But no, you shouldn't. Separate the sentences or move the clarification within.

I am wondering if you know any publications, blogs or websites -- particularly those interested in tech or the cloud, big data, mobile applications, info graphics, etc. -- who are seeking new writers right now?

or

I am wondering if you know any publications, blogs or websites who are seeking new writers right now? I'm particularly looking for those interested in tech or the cloud, big data, mobile applications, info graphics, etc.

Dashes are meant for interruptions or changes in thought, including statements of clarification. Having one after the question has already ended is like interrupting a break. For more on em-dash, see here.

Whether it is acceptable could depend on the type of publication, is it technical? - or historical? - or maybe, ye olde english prose?

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As you can see, you can have dashes after question marks, though the sentences can also be easily rearranged to avoid this construct. Personally I feel its uncommon, and not suitable except in a few cases (e.g., above I am basically paraphrasing a bullet list in sentence form) - but you can make it work :)

There is nothing wrong — informally at least — with using a dash after a question. The dash is a great way to indicate an abrupt change of thought or a parenthetical statement, and sometimes this may be useful after a question is complete.

In your example sentence, the question is really only complete at the very end, so the first question mark is not necessary at all:

I am wondering if you know any publications, blogs or websites who are seeking new writers right now — particularly those interested in tech or the cloud, big data, mobile applications, info graphics, etc.?

Note that "I am wondering" is actually a statement, so what you have here is informal use of the question mark anyway. That is, it is used to indicate rising inflection as per reported speech, rather than an actual question.