Google sites rocks!
For the syntax highlighting I have written a ruby script which generates rtf html with inline css that works on safari, open office and keynote (only safari, neither firefox or chrome!). I just have to copy the code, type a keyboard shortcut that will trigger quicksilver to run the script that process the clipboard and put the highlighted code in the paste buffer.
For screenshots, I am using skitch
To use the custom URL wiki.21croissants.com, you must change the CNAME record with your domain host.