Brad Templeton writes about overly structured forms, one of my top UI peeves. The inability to copy and paste an IP address into a form with four separate fields has annoyed me, oh, probably hundreds of times. Date widgets annoy me slightly less. Listen to Brad when designing your next form, on the web or off.
The opposite of overly structured forms would be a freeform editing widget populated with unconstrained fields blank or filled with example data, or even a completely empty editing widget with suggested structure documented next to the widget — a wiki editing form. This isn’t as strange as it seems — many forms are distributed as word processor or plain text documents that recipients are expected to fill in by editing directly and return.
I don’t think “wikiforms” are appropriate for many cases where structured forms are used, but it’s useful to think of opposites and I imagine their (and hybrids — think a “rich” wiki editor with autocompletion — I haven’t really, but I imagine this is deja vu for anyone who has used mainframe-style data entry applications) niche could increase.
Ironically the currently number one use of the term wiki forms denotes adding structured forms to wikis!