Adobe Flash Player is the standard for delivering high-impact, rich Web content. Designs, animation, and application user interfaces are deployed immediately across all browsers and platforms, attracting and engaging users with a rich Web experience.

Install Flash Player 9 in Ubuntu Dapper

First you need to edit the /etc/apt/sources.list file

sudo gedit /etc/apt/sources.list

add the following Repository list and save the file

deb http://3v1n0. dapper 3v1n0
deb-src http://3v1n0. dapper 3v1n0

Now you need to copy the key for this Repository list using the following

sudo wget http://3v1n0./EDD1E155.gpg -O- | sudo apt-key add -

Update the source list using the following command

sudo apt-get update

Install flash player Plugin using the follwoing command

sudo apt-get install flashplugin-nonfree

One more method is you can install this from the source code.If you want to install source code download flashplayer from here

extract the tar.gz file and copy  libflashplayer.so file to /usr/lib/firefox/plugins or ~/.mozilla/plugins (check where this directory is located in your ubuntu desktop)

More applications Repository list  can be found  here