I signed up to MediaWiki.org on 1 April 2006.
Contributed Fixes 
I contributed fixes to the software regularly since March 2006 (first I've only contributed Hebrew language updates, then I started to suggest other fixes), although they were not always accpeted. On 19 June 2006, I was given an access to the Subversion reposity, and was able to directly commit fixes.
Commited Fixes 
- Bug 2069 – Merge the LanguageUtf8 class into the Language class
- Bug 2773 – The print mode of page is not shown as RTL on RTL wikis.
- Bug 5357 – Add the icon near the user name also in RTL interfaces
- Bug 5387 – Block log items on RecentChanges don't make use of possible translations
- Bug 5409 – Don't show "show/hide patrolled edits" ("showhideminor") when patrolling is disabled
- Bug 5536 – Set "edithelppage" as a message used by the site language, not by the user's one
- Bug 5583 – Update the rollback message ("revertpage") in English
- Bug 5585 – Makesysop outputs a completely different log entry than Userrights
- Bug 5587 – Clean up the languages from references to the Groups special page
- Bug 5592 – Set the logs fixed text in Recent Changes as the site language, not the user's one
- Bug 5593 – Fix "Bureaucrat Log" to "Rights Log" everywhere, including the message names
- Bug 5724 – Add direction marks to stop some annoying problems
- Bug 5846 – Add an appropriate documentation page for each user group
- Bug 5849 – Remove some hard-coded "wikipedia"s in the system messages
- Bug 5970 – Need to login to upload files
- Bug 6015 – Add spacing in the boxes "edit is minor" and "watch this"
- Bug 6032 – Plural support for 'undelete_short' in SkinTemplate.php
- Bug 6168 – Inherit Yiddish localisation from Hebrew
- Bug 6174 – Remove redundant "emailforlost" message
- Bug 6184 – Links to the user pages are always blue (known) in the Undelete page
- Bug 6185 – Add talk, contribs and block links to the log page
- Bug 6189 – Show an error to an unprivilleged user trying to create account
Hebrew language updates 
These bugs were used to update the Hebrew language regulary.
Main contributions 
My main contributions to the software (full list):
- Making the Hebrew translation up-to-date.
- Enabling translations for the ParserFunctions, and all the extension Magic Words.
- Enabling translation for extension messages.
- Merging the language checking scripts to checkLanguage.php, which also checks for ignored messages, can display and various forms, etc.
- Creating the script rebuildLanguage.php, to rebuild and sort message files automatically.
User map in Wikimedia Foundation 
ויקיספר (sysop, bureaucrat)