Since we link to outside blogs when answering questions fairly frequently, it doesn't seem unreasonable to link to your own if that's where the best answer is.
The question is whether you'll be tempted to link to your own blog when the post you're linking to is only tangentially related to the question, or only marginally useful. You might justifiably be slammed in rep if either is the case. And since it's your blog, your judgment of whether it is the "best" information available may be skewed.
For questions, the same logic applies, but you have to be even more careful that your question is welcome. The onus is on you, and so far it's seemed that questions are held to a higher standard than answers (since they're far more visible).
So, proceed with caution.