Like what type of information? This is potentially possible by modifying or creating a new registration from, but there are server side components that do things you might not be able to overcome. You can also configure the widget to collect certain profile fields (assuming you set them up)
What about custom locations dropdowns containing all Countries, Regions, and Cities of the world. These would be too large to enter as profile fields, as they contain 1 Million plus records.
This would all be possible via custom widget development with custom script extensions powering them. In particular, you could use a lookup text box in your form against custom ajax endpoints in your widget that call custom APIs that return filtered subsets of those lists.
Keep in mind that all of the UI is built from widgets calling back to out-of-the-box APIs that are also based on the same extensibility points. So, these techniques can scale from simple to complex needs.
