Bema judgement of bad works

Bible commentators generally believe that Christians will be rewarded for good works at the Bema judgement. I am unclear of the purpose of judging my evil/bad/worthless works after I am already saved and in Heaven. Is the purpose of that judgement to make the immortal me ashamed, guilty, or is it to make me fully aware of the extent of grace? Guilt and shame do not seem to belong in Heaven.