Tombo

A freeware, lightweight, hierarchical notepad app. Development is (very slowly) ongoing but although the latest version is in late Beta the previous version works very well. Pros - Lightweight - Free (and open source) - Regexp searching - Virtual folders (group any document with a specific keyword) - Optional encryption - Versions for Windows Mobile and (third party) Android - Data saved as a folder/file structure so easy to sync part or all. Cons - No markup capability (RTF or HTML support would be great) although it can open up another program of your choice to handle these.