One you may not have heard of is the UK based Interzone. Billing itself as "the UK's longest running science fiction and fantasy magazines (sic), founded in 1982", the subscription is, unfortunately, expensive after factoring in shipping to the US. Perhaps at some point they'll add electronic access (or, better yet, a Kindle
For a very limited time, you can win a one year subscription to Interzone (offer limited to those in ths US). Jason Sanford is sponsoring a contest, for US bloggers only, in celebration of the publication of his story "The Ships Like Clouds, Risen by Their Rain." Entering is easy - read the page, mention the contest and Interzone in your blog and let him know about it (details both on the contest page and he'll send them to you via email - as an added bonus, let him know you are going to participate and he'll send you a pdf copy of his article).