doit.im is a solid planner.
it uses david allen's Getting Things Done methodology- contexts, someday, inbox, etc... You can schedule things for today, tomorrow or another date. If you don't get it done that day, it'll just stay in your 'today' box. decent widget that shows your task for today, although kinda large and sometimes takes a couple clicks on start up. Plus it's FREE and can sync to a web account if you'd like to use it on your computer
I use this for basically everything. I use a calendar (Business calendar beta) only for things that HAVE to get done at a certain time (e.g. meetings). Everything else- goes in to doit.im.
Hope this helps- good luck!
