I have discussed online forms systems many times and for a good reason: They keep getting better. And just when I think that there's a "best" system, along comes another that tops the last. So it won't surprise you to hear that I've found the best Web form system to date - Frevvo.

In many ways Frevvo builds upon techniques other forms systems pioneered (the use of AJAX for example), but Frevvo not only employs those techniques as well if not better than its predecessors it also adds a number of features such as XML support and the ability to self-host that moves it into a different category.

When you register with Frevvo you can choose to use either the standard or XML edition of Frevvo. The standard edition provides a straightforward set of form design and management features while the XML edition provides “applications,” which combine the complex mixture of forms, XML schemas, and documents into manageable packages that can be exported to other users or uploaded to other Frevvo servers.

Frevvo forms can be created from scratch, from provided templates, or by copying existing forms. The palette of controls contains just about every type you could need including tabs and collapsible sections, and controls can be modified with customized validation rules specified as XML schema regular expressions.

You can also add rules to dynamically modify the behavior of forms, for example, to make certain fields visible or enabled depending on other fields.

Deploying a form can be done in several ways: Embedded in a Web page; as its own Web page centered and automatically sized; as a link that can be e-mailed or linked to from a Web page; as an HTML iFrame; or as a “raw form” link which allows you to e-mail a partially filled form that displays by itself in a page. The only requirement for the user’s browser is JavaScript support.

The results of filled forms can be e-mailed to you as well as downloaded as Excel spreadsheets or examined individually. The Submissions page of your account allows you to select a subset of submitted data by form name and also graphs the activity of the form.

The XML Edition can be extended with a free database connector so that forms can read from, and write to databases, and the results of XML-based forms can be sent to other services. For example, a Frevvo form can be used to directly update data in a Google Docs spreadsheet (how cool is that?!).

Mark Gibbs is a consultant, author, journalist, columnist and blogger.