This is mostly for my own reference, but others may find it useful:

If you have QuickSilver on your Mac, you can set a timer that will put large text on your screen after a set amount of time..  good for easy reminders that don't involve a calendar event. Like if you need to move your car in 90 minutes to avoid a ticket for instance.
  • Use shortcut to open quicksilver: (Command + Space, or whatever you have it set to)
  • Type "." to enter text mode
  • Enter the text you want displayed
  • Hit tab, select "Large text", hit CTRL + ENTER
  • Now type "after" to get "run after.." (or choose run at, etc)
  • Then select it, and then input a time interval (10m, 1h, etc)