I'm not sure if it's been mentioned here or not, but another of the seemingly endless series of journals to monitor is the International Journal of Astrobiology (IJA), which one will note is distinct from Astrobiology. To be sure, both journals are fairly pricey; however, in my opinion both have fairly interesting and informative papers.
For those who don't have access, I believe if you complete IJA's free registration you get complimentary access to an issue (which, I believe, changes after a period of time). In any event, all of the articles from the January 2005 issue of IJA are available here.