view-source:http://www.google.com/

this in location bar to view page source of google.com.
So i have made this Bookmarklet to view page source: View Source (So you can drag this to your bookmark toolbar to have quick access).

Similarly you can type javascript: in your location bar to open java script error console.

Update1:
Key Board Shortcut: Use Ctrl+U to view page source

Related Post:
Firefox About Pages
Little tweaks with javascript : Bookmarklets.
Open webpages in sidebar

• Imagination Cubed
• Wetpaint Please Touch – Create Your Own Masterpiece!
• Artpad
• FlashPaint
• Sketchr (also available at http://www.queeky.com)
• Scratchpad
• Online Paint Brush

HTML < canvas > Based:

• Paint Chat [designed by me ]
• Canvas Painter
• Canvas Paint (resembles to MS paint)

Java Based:

• Drawing Online
• ZEwall: Online Painting
• JPainter : Online image editor

Related Post :
Paint Chat !!
Web2.0 Applications

Firebug integrates with Firefox to put a wealth of development tools at your fingertips while you browse. You can edit, debug, and monitor CSS, HTML, and JavaScript live in any web page.

Firebug is firefox addon that helps you in webdevelopment with
its powerful feature such as javascript debugger, Inspect and edit HTML, Tweak CSS to perfection, Monitor network activity, Explore the DOM and many more. Feature I like most is its quickly diagnosing problem, it allows you set break points and checking intermediate values of variable for javascript thus making a great javascript debugger. Many times you are stuck at where did the code went wrong so in way its a lot useful in saving time.

I also like is its inspecting html and modifying html and css on fly and see the results with helpful tooltips. It also help in positioning of divs, images with its nice feature of visuallizing css metrics with ruler and box model coloring(HTML inspecting).

It other great feature is its interface which is comes with browser window split in two halves one for your website and one is extension interface (though it also can be detached from it). I am also a fan of Web developer toolbar extension but what it lacks is a java debugger and this great interface but both are a must of a web developer.

Related Post :

• If you want to develop firefox extension..

I had made this app which uses paint brush to express yourself and share with others. This uses HTML:Canvas for drawing graphics using javascript, so no sluggish java applet and flash. It uses XMLHttprequest to synchronize paint screen with server. You can share this url with your friends to have a chat with paint brush and use Refresh !! to update your paint screen with that of your friend.
Read about Paint chat.
Try It out : Paint Chat

Updated: I have added feature for filling up whole background with color and also the transparency feature.

Related Post:
Shout-Box

java -version

The output should look something like this if everything is well

java version "1.5.0_05"Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0_05-b05)Java HotSpot(TM) Client VM (build 1.5.0_05-b05, mixed mode)

If the version does not match what you just installed then you might have JRE/JDK installed previously

Multiple JRE/JDK installed

If you have multiple JRE or JDK installed (e.g. 1.5.0 and 1.4.2) and want/need to switch between them, you can use update-alternatives to do so.

Example: Choosing which java executable to use:

update-alternatives --config java

Example: Choosing which javac executable to use:

update-alternatives --config javac

And so on in that fashion for the remaining executables related to Java. You can look in /etc/alternatives to see what one can configure with update-alternatives.
Links : Download