There is an incredible amount of sheet music available on the internet, you just have to know where to look.
Here are the 5 Greatest resources for finding FREE Sheet Music on the internet. Guaranteed!
(I dont support stealing of music. This is only for learning purposes.)
The only Sheet music sharing site of its kind. This site allows you to trade and request sheet music from other people.
This is a comprehensive database of free and non free sheet music for all instruments and in all styles. They also have a section that helps you learn how to play piano. I would definitely check out their database. There is also a nice Pop and Rock section on this site.
EDIT: This site hasnt been updated in a while. They are great because they focus only on Pop and Rock music. It is a little bit difficult to navigate though.
This is Proof that Music Brings Strangers Together!
Another Site for original Rock and Pop sheet music. Most of the music you will find on this site is from before the 2000’s but they are the original sheets in PDF form. Take a look and see if you find something you like.
This is a web site that is compiled by musicians who upload their versions of music. They have a wide variety of Beginner to Advanced Sheet music ranging in ALL styles. They have music for all instruments here too!
Open source Contemporary and Classical instrumental music of a wide variety. They have over 1900 pieces of music including Scott Joplin, Mozart, Bach, Beethoven, and Traditional pieces. The reason why this web site is so good is because they provide you with open source music and they rearrange them for you. However, the next site is even better....
This 14 year old kid plays piano better than you...
Extra special!! http://imslp.org/
This is the GREATEST resource of Classical and some Jazz sheet music I have ever seen. It is incredible and a true work of art. It is a hub for learning and expanding your mind. There is more information here to last you 100 lifetimes. They provide you with ORIGINAL scores of all major pieces of music that are in public domain.