David-

I would look at either Xmod or Enterprise Forms for approval type features in a forms module (get them at www.snowcovered.com). Which one depends on what you want to do - EF has strong approval features and a very strong workflow engine. Xmod doesn't have the workflow engine but has many more features/capabilities overall - allowing you to use it to build many different types of modules. Unless you are building a business specific form that needs the workflow engine I would pick Xmod.  Xmod 5 should be coming out within a week or so with a large amount of new features.

You could also look at ListX which is the most powerful of all the forms modules but has a very steep learning curve unless you already know the sql language which makes it a little easier.