I also use a spreadsheet. At the top of each column, I list a story name and wordcount. At the beginning of each row, I list a market. I color code the cells between to indicate things like 'submitted', 'rejected', and... well, that's actually all I've got now, but I do have a color for 'accepted' I hope to use later.
I then use a second spreadsheet for each market, detailing things like pay rate, multiple and simultaneous submissions, how to submit, etc.
I just started using Grinder, but while it looks useful for finding new markets, I'm not all that comfortable using it or all my tracking yet.