There are several little gadgets (widgets) that WA has provided with certain componants. They usually hide in the install and are part of the wizard, or may even have their own entry.
A few Suggestions:
1: Captcha - Insertable on any page with a form on it.
2: Date Picker: A nice looking date picker calendar that can be applied to any text field.
3: Conditional Show/Hide: Highlight text/image/page area/etc... then click the button and apply the rules.
4: List Sorter: Ability to re-organize a database list based on a sort field. Basic move up /down arrows and save would work, but drag and drop would also be nice.
5: Restricted Text Area: Apply this to a text area so the characters are counted, and a limit can be placed on how many characters are entered.
6: Export recordset to XML
7: Checkbox 1,0: Applied to a checkbox, the checkbox instantly has a value of 1 if checked, and 0 if not checked. Currently the database would need a default of 0 if the submission is null for this to work - while this will solution would work even if the database is not setup as such. 1,0 can also have some other choices like Y,N or -1,0 or even allow for free form entry (ie: Phone Me,Email Me)
I'm sure there are many more...