We used to use our own suggestion form on the payment confirmation page (page seen after the user completes the checkout process) and it had a very high usage rate. Users gave us more feedback and suggestions via that form than through all our other communication channels combined.
I've since replaced that form with a button that links to our Feature Upvote page, but we get nothing. Hardly anyone even clicks on the link, much less actually leave a suggestion or even vote on other suggestions.
I really like the Feature Upvote page as a way to manage suggestions and allow for community voting, but it's not as much use if the vast majority of users never visit.
I'd really like to see a way to embed the Add Suggestion form on our own site so that users were presented with the text input field without visiting another page.