Hello folks,
The N900 running a linux os so there are many keyboard shortcuts available to us.Lets have a look of all the keyboard shortcuts and various light notification used in N900 for notifying and to start various process.
Notification lights colour:

1.Blue Color light is meant for Application notifications such as an IM or Text Or Email.

2.Orange Color light indicate the battery is getting charged

3.Green Light denotes Battery charge is full

Keyboard Shortcuts Inside the Applications:
1.Ctrl+Backspace takes you to taskmanager .
2.As Usual Ctrl + C for copy text ,Ctrl + V to paste text ,Ctrl + X and Ctrl + A for moving text .
3. Ctrl + O Used to open.
4. Ctrl + N: Used to create a new item .
5.Ctrl + S: Used to Save .
6.Ctrl + Z: Used to undo .
7.Ctrl + Y: Used to Redo .
8.Ctrl + F: Opens the search bar for searching .
9.Ctrl + Right arrow: Function as END key in pc move to the end of the word.
10.Ctrl + Left arrow: Function as HOME key in pc move to the beginning of the word.
11.Ctrl + Shift + P:Used to Capture the screen as image.
12.Ctrl + Shift + X: Opens ‘X Terminal’
Keyboard Shorcuts for Web Browser:
1.Ctrl + N: Opens a fresh window in browser
2.Ctrl + R:Reloads the current page also can be used to reload the feed in RSS Viewer
3.Ctrl + B:Opens the Bookmarks folder
4.Ctrl + D:Save a new bookmark of the opened site
5.Ctrl + S:Save the current page.
6.Circular Zoom:To zoom the webpage

Also 1.Volume Rocker can be also used to zoom.
2.Double tap can also used to zoom.
7.Press Space:To scroll one page down.
8.Press Shift + Space:To One Page up.
Email Shortcuts
1.Ctrl + Enter:To send the current composed email.
2.Ctrl + R:To open new window for sending the reply to the current reading mail.

Check Out Other Tips:
1.HowTo: Create a shortcut to a file on the N900’s desktop
2.HowTo: Browse the N900’s File-system using its Web-Browser
3.How to take the Red-Pill and install more apps on the N900

Thanks to Nokia Experts.

Being able create a file-shortcut on the desktop is a standard feature of all desktop environments like XP, GNOME, KDE, OS X etc. Unfortunately, the N900’s desktop doesn’t allow putting any kind of link on the desktop except if its a bookmark. So if you like having quick access to certain files from the desktop, there is a workaround through the browser.

In the following example, I will create a shortcut to the agenda.pdf file. Open the file-system from the browser (see my previous post) and navigate to the folder of the file’s location.

Press and hold on the filename to bring up the menu. Select Add Bookmark. Give it a name and Save.

This will create a bookmak to the file. Now add the bookmark on the desktop.

Thats it. The file can be launched directly from the desktop.

Not so nice parts of this hack:
Web-browser launches, bookmark-folder inflates with the links, and the shortcuts on the desktop are deceptive without the thumbnail.

created using MaStory on the N900