You can test many things with UsabilityHub, from logos to wireframes and even book covers, but you can't test everything under the sun (yet).
At this time you can't:
Test fully interactive prototypes, but the navigation test sections may be a good fit
Send participants to another website as part of your test
Request that UsabilityHub panelists provide identifiable information as a part of your test
Test adult material with our panel of testers, or anything that would be considered Not Safe For Work