I have been using Evernote for a while now for jotting down notes at the most opportune times (usually between right when I think of stuff and before I forget). It is great to have a note-taking app that syncs across PC/Mac, phone, and tablet. I use it to keep track of personal and business items (including consulting work and blog ideas). It just works well and the basic version is free. I know the paid version adds more data sync and an off-line option, but I hardly use the options available in the free version. If you need to keep track of things on the go across many devices, you cannot go wrong with Evernote. Highly recommended!