I want to study geometry and was looking for some book that has lots of theorems and covers almost all Euclidean geometry that is needed for High School and Maths Olympiads. Thanks.
Probably on of the best problem book which covers geometry, especially recommended for olympiads: http://students.imsa.edu/~tliu/Math/planegeo.pdf
http://www-math.mit.edu/~kedlaya/geometryunbound/geom-080399.pdf (contains many important synthetic methods with a bunch of exercises and examples).
http://hoaxung.files.wordpress.com/2010/04/marko-radovanovic-complex-numbers-in-geometry.pdf (great article which covers complex numbers stuff)
“A Beautiful Journey Through Olympiad Geometry” is a book that presents all the theorems/methods that you need to know in order to solve IMO problems. It contains solved problems using these theorems, but also related problems that are left unsolved as a practice for the reader. Check out the book preview and download the book (pay what you want) here.
I actually got the links from artofproblemsolving site. You can find plenty of online material out there even on spesific topics of geometry.
Furthermore, it is highly curical that what level you are. You need to consider how much you studied and how far you want to go in geometry. Then, you need to pick carefully the book you want to study, regarding that information. Good luck.
The best geometry book I know: http://www.mccme.ru/~akopyan/papers/EnGeoFigures.pdf
Well there is a book "The Art and Craft Of Problem Solving" by Paul Zeitz. Its quite good, there is a section on Number theory and there is also a section on geometry. It will tell you of POP, etc. Wait! There is another book "Plane Euclidean Geometry: Theory and Problems" by A.D. Gardinier C.J. Bradley.