I would love to use the plugin for MediaWiki but I have already started using WikkaWiki (http://wikkawiki.org)...
So I want to see if I can create a plugin similar to the MediaWiki one that integrates the member tables, however I don't know where to start.
Can anyone provide some simple guidlines on how I would get started to accomplish this?

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I'm running wikka as well, and have it integrated with Elgg. Its not via a plug-in, but I stole a few ideas from some documentation on how to integrate with phpBB and applied them to Elgg to make it work. I'll try to package it up and provide it (as is, it won't be pretty or well documented, sorry).
I'm actually planning to move over to mediawiki after seeing what Dave and Ben have done with it here. Its much cleaner and better integrated than what I have done. Our wki is pretty empty right now, so their aren't really any barriers to moving.
You can see it in action at commun-IT.org
Great that would be cool. Maybe we can all figure out a way to optimize it to make it a approved plug-in.
I would like to move to mediawiki too. But my shared host does not have PHP 5 yet which is a requirment for mediawiki.
But WakkaWiki is very nice and it is much smaller so it is not a big deal that I can't move to mediawiki.
Thanks for sharing!
I've uploaded a few files that will point someone in the right direction (well, maybe not the right direction, but in a direction none the less) on integrating with wikkawiki. The key pieces are the your elgg db and wikka db be in the same database, and some code changes around line 808 of wakka.class.php that tell wikka to look at the elgg users table. 2 other files show one way to then single sign on from elgg to wikka (in the same way (roughly) that mediawiki plugin does)
If anyone has the time/inclination to clean this up feel free...
http://elgg.org/plugins/files/50/32/wikka.zip
./tim
Thanks, I am going to check this out over the weekend.
Also, if any elgg core deveopers can provide some tips on best practices of 3rd part integration so that we don't break anything when updates to elgg comes out it would be appreciated.
I'm using a script called particle links for the "Resources" bookmarking:
http://www.particlesoft.net/particlelinks/
I've been mulling over seeing if I can adapt Scuttle (scuttle.org) to integrate with Elgg, but haven't started anyting. I like scuttle because it support the delicious API, which opens up some cool possibilies and is more "social" than particlelinks.
My my needs, a "close enough" integration of mediawiki was sufficient. What Dave/Ben have done here is awesome, but a ton of finnicky work with CSS that I just didn't have the patience for. The mediawiki CSS structure is pretty horrific (IMHO). If anyone has found a nice "clean" mediawiki skin that would be a better starting point for an elgg integration (better than the monobook skin anyway) I'd love to hear about it.
./tim