NOTE: Must have considerable MediaWiki experience, not just PHP and CSS.
1) MediaWiki Upgrade: I have a MediaWiki site that I tried to upgrade. The upgrade worked, but I receive an error when I try to access the site. The site also has links to two MediaWiki sister sites. I tried to upgrade those, but received errors so wasn't able to upgrade. I suspect that one issue may be a problem with the .htaccess file. There are probably several other issues.
2) Extensions: A couple of MediaWiki extensions were modified to make it easier for users. Those may need to be modified to work with the upgrade. The site also has several custom extensions coded in PHP that will probably need to be modified to work with the latest MediaWiki upgrade.
3) CSS: Lastly, a couple of files in the Vector skin folder were modified to add Facebook, Twitter, and email functionality. Ideally, that code should be moved to MediaWiki:custom.css and modified (if needed) to work with the latest version of MediaWiki's Vector skin. A few other css changes were made and may need to be moved to the MediaWiki:custom.css file and modified for the latest upgrade, as needed.
If this sounds like something you could easily handle, please provide a little detail on your experience with MediaWiki, customizing MediaWiki extensions, PHP, and CSS. It may also be helpful if you know how to work with MySQL.
4) If selected, we would begin by letting you take an hour to look at the site to see what errors you find so that you can provide an estimate of how long it would take to fix the error messages, css, etc. In the end, I would need you to keep track of the changes you made (if you prefer to do a file comparison using track changes, that would be fine).