I was recently introduced to microsoft's tool that analyzes managed code assemblies called FxCop. It points out possible design, localization, performance, and security improvements against a pre defined set of rules (and also accepts custom rules). At first I was unsure how to go about using it as it seems to be aimed at software developers (.exe and .dll) . Its easy to get around this with the following steps:

1)Create a new folder (i.e C:\Code Analysis)
2)Publish your web application into the new folder
3)Open FxCop and add all the dll files from the newly created bin folder  to be scrutinized.

Lots more info / docs available here on msdn and you can also download fxcop free