Redline CAD drawings

[cadmando2]

Hey every one,
I’m looking for away to mark up “redline” autoCAD drawings without printing them out.
I do remember some program and a pen at one time, but I don’t matter at this time. One of my engineers is requesting me to look into it, my be some thing that could also be used out in the field in a laptop or on a desk top PC.
Dose anyone have any suggestion of a good product to use?:)

[NBC]

If you 'print' the dwg files to a dwf format, you can electronically 'red-line' the dwf's.
This red-lining can be brought straight into AutoCAD

<p.s.> Thanks ReMark for actually posting some info about the software used to 'red-line' dwf' files and a link to it.
In my haste to post, i simply forgot to add that info.

[ReMark]

AutoDesk Design Review.

http://usa.autodesk.com/adsk/servlet/index?siteID=123112&id=8412111