If you need for the purpose of examination I think you already know of RD Sharma. But personally i think that if you do NCERT properly, it is enough.
I you wish to read good stuff in mathematics, pick up any book by Martin Gardner. I am sure you will love it.
Pick up any topic you complete from your NCERT and look to the net for more challenging problems.
If you wish to do olympiad problems get 'Olympiad mathematics' by Mr. Singhal (i donot remember his initials, but its a good book)
If you wish to base your mathematics for IIT prep and all, try viewing videos on calculus basics on youtube.
However, be warned that class 9 is a very tender time to start such challenging things. Do not get bogged down if you do not get something. Probably you ought not, understand.
And read light books on mathematics. There;s a lot more to maths than exercises in standard books. Read any book by gardner. That's my foremost suggestion.