Well, last month's "Link of the Month" post went well...
I've still got mixed feelings about the Duotrope situation. I can see ways in which their site can be useful and provide enough value to be worth $5 per month. But I've gotten such a negative sense from how the folks behind Duotrope have handled the transition that I'm really disinclined to be a part of funding the site going forward.
So I've been working in recent days on doing my submissions without using Duotrope. For the most part, it's been going fine. With that in mind, here are some links that other folks might want to keep in mind if they aren't going to use Duotrope.
Ralan.com - If you're writing speculative fiction (SF, fantasy, horror) then you should be able to get nearly as much market information by going to Ralan as you could get at Duotrope.
Dark Markets - For horror-specific information, this site looks to be very useful.
Google Drive - If you're going to be tracking your own submission information manually, you'll most likely want some form of spreadsheet. You could certainly use Excel or another PC-based program, but if you don't already own software like that, Google Drive is a free alternative. (If you do use a PC-based program and want an easy way to have access to it on multiple computers, Dropbox is a good alternative.)
Sarah Hans' Blog - One of the things I liked on Duotrope was its calendar of upcoming submission calls. A decent percentage of the information from my Upcoming Deadlines posts was drawn from that calendar. Sarah puts up monthly posts with quite a few submission calls.
Hopefully, if you decide to go Duotrope-free, some of those links will help out. If you have other links you'd like to recommend, please feel free to note them in the comments!