Free GTD for Notes - eProductivity Essentials
The people who made the Getting Things Done-enabled Lotus Notes email-template that I use to get my things done have expandede their product line to include a stand-alone edition of eProductivity which (because it is stand-alone) does not require you to change the design of your email database.
The stand-alone edition also comes in a free version called The Essentials Edition.
I have bloggede about eProductivity and the Getting Things Done way of working a couple of times before. It really helps getting a firm grip on your commitments.