Reusable Menstrual Pads. 
Quite controversial for some however they're very cost effective and bloody cute (excuse the horrible pun.) You can get them in many kinds of patterns and with many different fabrics and asorbtion levels. Or, like me, you could try make them yourself :)
Attached is a photo of the first pads I ever made :) 
They're so much more comfortable than disposables and better for your body too. There are heaps of chemicals in tampons and pads and that horrible cotton. 
There is also a thing called menstrual cups. It sounds exactly like it is. I haven't yet tried mine but I will be tomorrow. Quite excited to so that I don't have to use tampons. :)