John Tynes just released Meta Action, an incomplete set of rules for running modern action with the D20 ruleset. At first glance it looks interesting enough. It retains hit points, since it’s intended to simulate action movies and thus can be less realistic, but more or less does away with classes. Your Charisma bonus is added to every roll, since action heros are good looking.
Without revamping the combat system, though, I’m not sure the ruleset works. PCs are going to get hit all the time, particularly since you can pump skill points into your ranged or melee attack bonuses. A level 1 character with a 14 Charisma (say) can easily have a total of +7 to hit right off the bat. Even level 0 NPCs can be fairly deadly. Three goons with shotguns are terrifying.
The Dog Squad is neat, though. It’s a cool little campaign concept that goes with the Meta Action rules. There’s enough there to work with.