- SPSecurityTrimmedControl. Trimming the UI base on the current user's permissions. Possible values for the different parameters; read a blog entry from Zac Smith, or this one.
- Showing different content for authenticated and anonymous users: read her.
- Hiding the sita actions menu: read her.
- Enhanced SPSecurityTrimmedControl. Open all the possibilities you can think of... (winsmarts.com)
- Creating your own custom wrappers. Do it all yourself! (Waldek Mastykarz)
- EditModePanel. Display different controls and elements if the page is in Edit or Display mode (WCM). Can be used to hide navigation, adding inline CSS to override classes to use different formating... (Chris O'Brien)
Related to html filtering and cleansing:
- SuppressWebPartChrome to remove all extra html-code and display ONLY the content. Web part property. Check out Waldek Mastykartz article.
- Remove or clean non-compliant html - override the Render method; read here.
Hiding elements when printing:
- CSS 2 styling and different style sheets for different medias are another. Read here.