Have you ever wanted to your character to do something incredibly heroic, but not been able to find a power or feat that does what you're looking for?
With Heroic Exploits, you can allow your character to do something special, so long as it falls within the purviews of your character's skills or abilities.
To use a Heroic Exploit, all you have to do is spend your action point at any point as a free action. Instead of taking an extra action, you can do something particularly heroic, such as turning a botch into a normal miss, or leaping in front of an ally to take a hit for them.
Really, you can do pretty much whatever you want, so long as it is something that your character could logically do, and so long as your DM approves of the action you wish to take.
AMdG