Having multiple monitors is great. You have a lot more desktop real estate to use. But there is one annoyance in Ubuntu that has irked me for a while. By default my Ubuntu installation treated both of my monitors as one large desktop. If I maximized a window, it would stretch across both screens. Finally I figured out how to prevent this. This method assumes you are using hardware accelleration along with Compiz, and Ubuntu is already set up for multiple monitors. Here are the steps:

1. Start the CompizConfig Settings Manager, which (if installed) can usually be found under System -> Preferences.
2. Under the "General" section, click on General Options. Go to the Display Settings tab.
3. Deselect the "Detect Outputs" option.
4. Under "Outputs", there will be one item listed, e.g. "2880x900+0+0". Select this item, and click Delete.
5. Click on New, then enter the resolution of your first (normally left most) monitor, followed by "+0+0". For example: "1280x800+0+0". Then click Close.
6. Click on New again, then enter the resolution of your second monitor, as above, but instead of the first 0, enter the horizontal resolution of the first monitor. For Example: "1600x900+1280+0". This tells the system where, in relation to the first monitor, the desktop space of the second monitor begins. Then click Close.
7. The setup should now be complete. When you open a window, it won't appear half-way on one screen and half-way on the other, and if you maximize, it will fill only the monitor it's currently on.

The guys from StumbleUpon have launch a service called su.pr. It's basically a URL shortener, but with benefits:

1. It can automatically post your URL to Twitter and Facebook
2. It puts the URL into the StumbleUpon database, so that people will find it while stumbling
3. It tracks clicks on the URL so that you can see how many people follow the link

A number of linux applications and tools are already extremely useful. On my installation of Ubuntu 9.04, some of my most used applications are Gnome-DO, Pidgin, and Open Office. Their built-in functionality is great, but you can go even further! Here are some links to find out about really useful extensions and plugins for these three tools.

Gnome-DO: 8 Most useful plugins for Gnome-DO

Pidgin: 10 useful Plugins To Spice Up Your Pidgin

Open Office: 8 Essential OpenOffice Extensions

Hopefully you can put these to good use!

Enjoy!