The flags in the first Assassin's Creed game. Forget about doing that one.
Yeah, that the game has collectable flags but doesn't keep track of them whatsoever is annoying, but at least they're not tied to anything other than health/sync, which you increase and eventually max out the further you get into the campaign, anyway. I played through the game a second time prior to the release of Revelations and again decided against collecting them for those very reasons.