I've used Stikipad. I originally selected it because it offered ad-free pages. Plus, Google AdSense could be enabled--- an opportunity for me to get some revenue to pay for hosting costs. It also had a great template allowing you to track a tasklist (add list items, marking them off as completed). Another benefit: access control could be set by page --> limiting who can see the page, who can edit it, etc.
Why I moved off StikiPad? You could have multiple wikis, but once the first was created, all new wikis were extensions off the original site URL. This created a long and strange URL. No one seemed to find my content on StikiPad. It was not easy to add neat content like images, videos, etc. I paid in advance for 6 months service -- that ended a long time back. I've never heard from them since. It seems that the support team is 'missing' and the service is just hosting out in the Web on its own. Many anonymous edits have been made to support pages and it appears no one is 'watching' from the StikiPad team. Unless things improve there, I'd stay away from this site. I've already moved all my content off the service.

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