I started using Outlook's calendar feature last year and I love it. I put in all the deadlines and set a reminder date, and up pops a reminder window with everything - column dates, contest entries, word counts, etc.

I also subscribe to the online Writers Market and keep track of submissions there.

Have you read Julie Hood's "the Organized Writer." It's fantastic, and it's downloadable to put into a notebook. She also sends out monthly reminders. Parts in the book have file tabs already made! Great resource.