One of the most useful custom WFFM fields we use is a custom hidden token field. I’ve used this on several projects for various reasons.
Hopefully a very simple one, however unfortunately it is not possible to add snippets of text in the forms, only to the header/footer or section titles. We often have to provide additional details which may also include HTML links/content.
We solved this problem by creating a custom Label field. There is not suitable existing field to inherit and extend, but it’s such a simple field we can inherit from the
CssClassControl field as a base.
A common field requirement seems to be a checkbox which also allows some HTML text, such as when including a checkbox that the user agrees to some Terms & Conditions, Privacy or Legal policy. It’s usually a requirement that links to the policies are provided within the text.
There’s nothing out-of-the-box with WFFM but it’s simple enough to create a custom field.
This is a re-post of an answer I provided on Sitecore StackExchange.