Speaking of Halo 3's water, awesome lighting
The water discussion also reminded me of the green outline debug mode that Frankie discussed in the Halo 3 updates where he'd talk about walking around with it on, the suddenly stumbling upon a fully rendered river because the effect ignored the water.
I wish they'd make that an actual skull, I know they re-used it for the H3 sniper scope and various Reach weapon scopes and the vehicle viewscreens in H3 and Reach. But it'd be cool to have something 'trippy' as a skull or effect.