Heroic statues are one of the more unappreciated structures in the game. Most people realize that they buff units fairly, adding 50% more damage and armor, but their other benefits are often forgotten.
They double experience point earnings, increase your command point limit by 10, and reduce the cost of infantry by 4% per statue, which doesn't seem like much, but it certainly adds up with large numbers of units as well as with expensive units. The last and probably greatest relatively unknown benefit is that the statues prevent the effects of Boromir's infamous horn for units within their area of influence!
So, what are you waiting for? Get out and use those statues!