The daily reputation cap is set at 200 points, not including reputation gained from bounties.
The main advantage of reputation, aside from prestige, is that reputation unlocks new privileges on the site. These are listed on the privileges page, located here on Stack Overflow.
For example on your Stack Overflow account, your next 'unlock' is at 1,000 reputation. This will give you the established user privilege - in summary you get an expandable usercard and the ability to view +- on votes as well as the net score.
It should be noted that the reputation tied to privileges is less on beta sites and even less on private beta sites. This allows these sites to get going by allowing low reputation users to moderate when there has been little opportunity to gain rep.
You may also want to see the faq on reputation and the comparison of rep requirements on all sites.