Active Desktop Statusbar Icon by Nicolai: This tiny app can be found in the Application Manager under Desktop. It sits in the status bar area near or next to your wifi signal icon and does one job brilliantly. It tells you which desktop you are looking at, so that you know which way to swipe depending on the number of desktops you have. I currently have 6 active desktops so my 1st desktop would be quickly reached if I swiped right.
Touch Search 3.1-1 desktop widget by Brent Chiodo: Allows one to search the web quickly and easily from the desktop. There are a number of search options available namely Google, Ebay, Amazon.com, Wikipedia, Dictionary.com, YouTube and many more. The widget is easily customized and there are extra search engines available to download from the applications home page. One of my most used widgets.
Conky 1.8.1 by Darren Long: Conky can display just about anything when it comes to system monitoring on your N900. Extremely useful if one is running multiple things at one time and you want to know what is using up your resources. Conky can be downloaded through the Application Manager under Desktop or from their home page.