There are thousands of utilities to help in productivity. But using the following improves it a lot.
Essential PIM - A nice portable freeware which can store all notes, addresses, schedules and appointments. Available from http://www.essentialpim.com/
Flashnote - A quickly accessible background application which can be used to store and access all immediately accessible content in a categorical manner using a short cut key. With little organisation, this utility can rock. Portable version of the application is available. Available from http://softvoile.com/flashnote/
Clipdiary - A quickly accessible background application which captures whatever is copied on to the clipboard using Ctrl+C. It orders the copied content in a chronological manner helping in retrieving older content in an easier manner. Unfortunately, now the product has been made commercial from freeware. If you could find a freeware version, use it. Can be made portable. Available from http://clipdiary.com/ (Note: Only commercial version is available from the given link.)
More utilities will be added soon.