If you're interested in getting something coded special for you, I'd recommend one of three options:
- Post your request to http://jobs.wordpress.net
- Post your request to the WP-Pro mailing list
- Send me an email off the forum (eric [at] eamann [dot] com)
This should be a fairly easy application to set up with shortcodes. I.E. [pluginname level="author"] Content for Author-level[/pluginname][pluginname level="contributor"]Content for Contributor-level[/pluginname] etc ...
Or something along those lines. Like I said, contact me offline if you want to talk more about it.
As far as using custom fields, I'm not 100% sure how you'd do that. Maybe have one custom field containing content for authors, one for editors, one for subscribers ... and then a plugin that applies a filter to your custom fields - displaying only those that match the current user level. I haven't worked much with custom fields, though, so I'm not sure exactly how it would work.