Following are some of my favourite firefox add-ons
1. DoNotTrackMe
Protect your privacy. Stop companies and advertisers from tracking your browsing and sending you spam email.
2. AdBlock Plus
 Blocks annoying video ads on YouTube, Facebook ads, banners and much more. Adblock Plus blocks all annoying ads, and supports websites by not blocking unobtrusive ads by default (configurable).
3. BugMeNot
Tired of creating multiple accounts on various websites, bypass compulsory web registration with the context menu via www.bugmenot.com.

4. DownThemAll

The first and only download manager/accelerator built inside Firefox!

5. Flash Video Downloader
Flash Video Downloader helps you to download any video (flv, mp4, HD) from YouTube-like, Facebook, Break, Metacafe and more in one click. You can download mp3, music (iPod), avi and more. Download Flash games. Download Helper.

Recently I came across Ubuntu version of WinUSB, a popular tool to make bootable Windows USB.
I found it to be easy and simple.
Here is the official website, where you can get this tool.

Rsync is a fast and extraordinarily versatile file copying tool. It can copy locally, to/from another host over any remote shell, or to/from a remote rsync daemon. It offers a large number of options that control every aspect of its behavior and permit very flexible specification of the set of files to be copied. It is famous for its delta-transfer algorithm, which reduces the amount of data sent over the network by sending only the differences between the source files and the existing files in the destination. Rsync is widely used for backups and mirroring and as an improved copy command for everyday use.

Rsync is installed in Ubuntu by default. If you need a GUI front-end, install Grsync. It is available in Ubuntu Software Center and also Synaptic package manager.

Usage:
Local backup

sudo rsync -azvv source/ destination/

Remote Backup

sudo rsync --dry-run --delete -azvv -e ssh source remoteuser@remotehost.remotedomain:/path-to-destination/

An explanation of above options to commands:

• --dry-run This tells rsync to not actually do anything. It will just write a log of what it would do to the screen. Once you've made sure everything will work as you expect, you have to remove this option, and run the command again to perform the actual backup.
• --delete deletes files that don't exist on the system being backed up.(Optional)
• -a preserves the date and times, and permissions of the files (same as -rlptgoD).
• With this option rsync will:
  • Descend recursively into all directories (-r),
  • copy symlinks as symlinks (-l),
  • preserve file permissions (-p),
  • preserve modification times (-t),
  • preserve groups (-g),
  • preserve file ownership (-o), and
  • preserve devices as devices (-D).
• -z compresses the data
• -vv increases the verbosity of the reporting process
• -e specifies remote shell to use 

 Source: Ubuntu Community

If you are anything like me and spends a good amount of time on computer, your eyes may say you soon that "Hey! it's fantastic. Give me some comfort or else I'll take yours". You may soon face dry-eyes or sleeping dis-orders. Let's take some precautions to save them.
Now I'm not gonna discuss something like don't stare without blinking your eyes or maintain some distance from monitor, but here is a way to optimize your monitors brightness automatically according to the time-of-the-day and temperature.
Redshift adjusts the color temperature of your screen according to your surroundings. This may help your eyes hurt less if you are working in front of the screen at night.
To install it in Ubuntu:

sudo add-apt-repository ppa:jonls/redshift-ppa
sudo apt-get update && sudo apt-get install redshift

To start the application, first find the coordinates of your location (lat:long). Then

redshift -l lat:long (eg: redshift -l 17.033:55.20)

For latest version and also Windows installation, visit the official website.

In my previous post, I mentioned a way to handle large integers by using BigInteger. Now I'm going to provide a very important usage of it. We often use for-loop. So here is the way to use it:

Ordinary integers:

for(int i = 1; i <= n; i++) {
 //Task to do
}

BigInteger:

for (BigInteger bi = BigInteger.valueOf(1);
                bi.compareTo(n) <= 0;
                bi = bi.add(BigInteger.ONE)) {
//Task to do
}

here n is a BigInteger variable.

Many of you might have wondered, as I did, how to deal with integers of say more than 50 digits or so. And might have thought about breaking the integer into parts or storing it in a string and parse letter-by-letter.
Java provides a class for such large numbers: BigInteger.
You can find it in the package: java.math.BigInteger
We can do some operations like addition, subtraction, multiplication, division etc, but slightly in a different way.
For detailed information on its usage, have a look at this.

Today I tried to a new project in eclipse and on clicking

File>New> 

I found

<No Applicable Items>

I'm not able to create any kind of project. Then I found a solution on ecipse discussion group.

There are some selections in the IDE in the upper right corner; Java, JAVA EE and Resource etc. It was set to Java EE. When I selected JAVA, I can now create new projects again