Tickle Me Outlook
The tickler file is another concept that I first encountered in David Allen's Getting Things Done, though its been around for quite a while. Definitions of what a tickler file is are on the web, but the basic idea is that you put reminders into a a file for each day and open up the file for today to see what you need to be reminded of. Probably the best summary I've found is the one at 43 Folders. Go read it. Heck, read the whole site if you're into GTD.
One key to making your tickler file work is recognizing what you'll use it for. I tend to use mine to remind me of next actions that I can't act on now but will be able to later. It sometimes also has reminders of next actions that I want to force myself to see and deal with in the future rather than now. I almost never keep appointments or someday/maybe things in my tickler file. Because of this, things in my tickler file tend to make it into my next actions lists, or occasionally on to my calendar, if they're urgent enough.
Anyway, there's quite a few ways you can setup a tickler file in Outlook. The simplest, and probably the most common, is to just use all day events on the calendar. This lets you set a reminder and it will of course show up on your calendar for the day. When you want to push something out further than a month, you can just put the tickler item on the 1st of the month in which you want to be reminded. If you use the calendar regularly already, this helps make sure that you see the stuff in your tickler file.
Of course, there are other alternatives, depending on how you use Outlook and how you want to use your tickler file. One is to use tasks. Tasks also have reminders, so if you appreciate the reminder dialog you can use it. Tasks can make sense if you also use them for next actions that have no date associated with them. Its pretty easy to just filter out your tasks based on whether there is a start (or due) date - those with it are your tickler, those without are your next actions. In Outlook 2007, you can now show tasks on your calendar, so tasks with a date seem like the perfect fit for a tickler file. You can see them on your calendar and it's easy to convert them to next actions - just remove the date.
You can also use flagged mail items or the journal to keep a tickler. Flagged mail has due dates and journal entries have start dates. Additionally, in Outlook 2007 flagged mail shows up on your task lists, making it easier to think about mail as either next actions or tickler items.
Ultimately, the goal is to not let anything slip through the cracks. The tickler file can be really useful in reminding you of "stuff" when you need to be reminded. Of all the options above, I have to admit that I've used each one at some point (I've never used contacts with their birthdays to track tickler items, but technically, it could be done). After going through all these ideas I am now settling on tasks with start dates. The main benefit to me is that it's so easy to make them into a next action. I can also add reminders if I think I need to, and they fit in with everything else I keep in Outlook quite well.