Most of the applications I work on have very straight-forward components and not a lot of complex functions/methods. I would only be testing whether or not they worked at all, rather than if they worked in a wide-array of situations. [...] For example, unit-testing a simple news list and detail page is probably overkill. Sure, you can test your classes by simple instantiating them but that only goes so far. My new method involves using SimpleTest's Scriptable Browser to actually crawl webpages and ensure that the proper data is being displayed.
He includes a few snippets of code to show how to implement SimpleTest's web test functionality - one that just checks a HTTP response values, another that checks for text on the page, one testing for a login on an admin page and a test for add/edit pages to ensure valid loading based on URLs/links.