Post submission form with custom fields?

I’d like to add a form to a site that will allow registered users to create posts. I need those posts to save in the submission process an extra field – a meme-selection field. You can view a mockup of the form here and thereby understand what I want:
https://irritatd.custombusinessmarketing.com/submit.html

I was thinking of using the User Submitted Posts plugin, but I don’t see anyway to save the meme selection along with the rest of the post. I was thinking of saving it in a custom field, but I see no way to add a custom field to the forms created by that plugin.

Is there any plugin I could use to accomplish this functionality? Or a guide to developing such a plugin?

Thanks,
Travis