Do you live with an individual that you support? If so you may be able to claim the eligible dependant credit.
One common instance involves parents who live with, and are being supported by their children. If the parent is earning a low enough income level such that they are not utilizing their full basic exemption credit, the difference can be transferred over as an eligible dependant credit.
To see if you or someone you know might qualify for the eligible dependant credit, the CRA website has more information at:
http://www.cra-arc.gc.ca/tx/ndvdls/tpcs/ncm-tx/rtrn/cmpltng/ddctns/lns300-350/305/lgbl-eng.html