DeepTrawl is astoundingly simple to use. Type in the URL of the site you wish to trawl, and click the big green arrow. The program leaps to work, racing through your site, and building up a catalog of spelling errors, broken links, and slow-loading images. It then presents this to you in an easy-to-use format. Each page with errors is listed; you can expand the list and click on an error, and then pick an option. For example, you may determine a "misspelled" word is someone's name and add it to the dictionary or you may say "Ooops!" and open the page for editing.
In addition, DeepTrawl allows you to define your own search criteria, using standard boolean conditions. This can be useful if, for example, your company address has changed and you want to find every place on your Web site where it was not updated properly. (It would have been nice to have the ability to use regular expressions for this feature, but you can't have everything...)
DeepTrawl allows you to set levels of sensitivity, to exclude minor errors or stylistic problems with no impact on functionality, or to pick up every small deviation from accepted standards.
Simple, fast, and thorough, DeepTrawl is a powerful tool if you have a large (>25 pages or so) Web site which is often updated or which contains many external links. The software comes in several versions, with the price dependent upon the maximum number of pages which can be "trawled" for a given site. The $49.00 "Tetra" version supports a maximum of 50 pages.