I was working on a project today that lead me to create this app for myself, and I thought I could share it.
Basically, Saev My Battery! let you reduce your brightness below the minimum possible, without your phone needing to be rooted.
For now, the battery saving will occur only with AMOLED displays (like the SGS2's screen), but I'm planning to add the reddish tint for other displays in the next few days.
Let me know what you think about it, if you find any bug, if you'd like some more features etc...
Thanks for being my beta testers fellow SGS2 owners