Windows 7 have a nifty feature which combines the windows of opened applications under the same taskbar button. If you don't like it you can always turn it off.
If you want to use only a song from a specific video, you can use it with the help of web converter. In this lesson I will show you how you can convert Youtube video to mp3 file.
If you use a lot of different usernames and passwords it is difficult to remember all of them. KeePass is an interesting solution where all your passwords are kept in one safe place and protected with one password.