Remarkable when it first came out, and still quite impressive, the Wikiserver iPhone app is now free. I'm not sure how long John intends to keep it free, but get it while you can. It's an entire webserver running Seaside and Pier, and a webkit client to display the pages directly on the phone, or you can connect to the server from anywhere else on the local WiFi segment.

Update: Looks like WikiserverPro for iPad is also free!

Update2: John just mentioned that both are free for 24 hours.  I presume he means all in a row. :)