Thanks to working on the aggregator, I've become aware of a lot of semi-forgotten projects. There have a fair number of slideshow presentations, for one.
For HTML conversion, there has been this:
I wrote a converter for use with Tiddlyclip, but I don't know if it was ever incorporated.
What I like about markdown is that it is a true standard that is supported by pandoc and other utilities and is used throughout the internet. It will likely be here in 30 years. Wikitext, on the other hand, changed between TWC and TW5 and might change again with TWx .
The new markdown plugin lets you use some wikitext, so you can get the best of both worlds.
Those discussions about which markup is better remind me of video tape enthusiasts clinging to their Beta tapes because the format was so much better than VHS. Of course I'm dating myself just by mentioning tape.