as far as i know i dont see why you cannot apply it outbound. outbound is traffic leaving your router so it makes sense to apply it ourbound.
forexample, below is an example policy-map that matches the yahoo.com class and drops the traffic. Lastly the policy is applied outbound to the Internet.
R1#
class-map match-all yahoo
match protocol http host "*yahoo.com*"
!
policy-map DROP_yahoo
class yahoo
drop
!
interface FastEthernet0/0
description TO INTERNET
service-policy output DROP_yahoo