Is it possible to boost skills beyond 100 points?
When my sneak is at 100, does a 25% bonus from the shrouded hood do anything?
I am currently trying to determine if keeping the hood around is useful or not.
Unlike in Oblivion, skills in Skyrim can be raised above 100.
This is probably most often used to fuel the Alchemy - Enchanting feedback loop, but it's also why the Fortify Restoration glitch is able to give you arbitrarily high stats.
Considering the specific case of the sneak skill... hidden is hidden. If you are never detected while you crawl around with 100% sneak skill, then another 25% is not useful.