If you are among categories of those students who could not score well in college you can aim to do well in the GRE. It will open new avenues for you.
The importance of GRE score in graduate admissions varies from program to program. Some graduate schools use the GRE as a cutoff while others consider it to off-set a low GPA. Additionally, other favoured evaluation is that where different sections of the GRE test could be weighted differently. For example, if you apply for Math or Statistics program, they will probably place more importance on how you performed on the Quantitative section than on Verbal and Analytical sections. Whereas if you apply for an English graduate program your verbal and analytical Writing scores will carry more weight.
Also some schools even use your GRE score for the selection of scholarship and fellowship candidates.