Been using Journler for the past few days and in a word "ROCKS!".
Way better than my previous method of puting it in a word document and organizing via directories. With this app, you have on unified repository of your notes which can embed URLS, PDF's, regular files, pictures etc. Integration iLife makes your digital life a bit more easier. Supports keywords/tagging and allows you to blog (supports blogger/wordpress) and email from within the app. You could also insert audio (great for meetings) and video if that pleases you.
My typical usage would be in writing down notes for research, and dragging a bunch of URL's there, link related files lurking in the hard drive. After which I could now draft the formal document on another word processor. The Journler fits this workflow perfectly and allows you one stop flexible repository of notes.
I seem to notice that the Mac community has a lot of high quality GTD-ish and digital life organizing apps. Most of them free! The high level of integration between apps is also quite noticeable. All in all helping a lot in the productivity department.
And before I forget, Journler is donationware!