[{ALLOW view All}] 
[{ALLOW edit Admin}]
[[UnlockMe]]

(Google results from 20 Feb 2007)
To every term we added "wiki", e.g. "MediaWiki wiki", "MoinMoin wiki" in an effort to exclude ambiguity.  We searched in Google without quotes.  Searches were conducted in Germany using an English interface.  Note that Incentive, Perspective and SamePage were not included due to the commonality of their names to English words giving unreasonable results.

%%sortable
||#||Wiki Engine||Google Res||License
|1|MediaWiki|133000000|GPL
|2|TiddlyWiki|1420000|BSD
|3|PukiWiki|1220000|GPL2
|4|MoinMoin|1180000|GPL
|5|DokuWiki|1160000|GPL 2
|6|JotSpot|1140000|
|7|TWiki|1120000|GPL
|8|PmWiki|1100000|GPL2
|9|TikiWiki|1090000|LGPL
|10|Socialtext|1090000|
|11|PBwiki|1070000|
|12|Wetpaint|1030000|
|13|[Wikka Wiki|WikkaWiki]|919000|GPL
|14|Confluence|878000|Commercial
|15|JSPWiki|875000|LGPL
|16|SnipSnap|702000|GPL
|17|PhpWiki|615000|GPL
|18|MoniWiki|603000|GPL
|19|Instiki|530000|Ruby GPL
|20|Wikispaces|480000|
|21|XWiki|440000|LGPL
|22|Friki|408000|ASL or LGPL
|23|UseMod|386000|GPL
|24|WackoWiki|339000|BSD
|25|StikiPad|323000|
|26|Wikidot|311000|
|27|Midgard Wiki|292000|LGPL
|28|bitweaver|266000|PHP
|29|Zwiki|228000|GPL
|30|FlexWiki|218000|CPL
|31|TracWiki|205000|Mod BSD
|32|VQWiki|163000|LGPL
|33|Oddmuse|156000|GPL
|34|SeedWiki|156000|
|35|GeboGebo|146000|GPL
|36|EditMe|142000|
|37|Giki|131000|GPL
|38|ErfurtWiki|94900|Public Domain
|39|Riki|92300|MIT
|40|ProWiki|72600|GPL
|41|Qwik|61700|
|42|yawiki|58500|BSD
|43|SubWiki|55800|Academic Free License
|44|UniWakka|47500|GPL
|45|telepark.wiki|47000|Custom
|46|ProjectForum|46400|Commercial
|47|MicKI|41000|GPL
|48|WikiDoc|37700|Per Server
|49|WikyBlog|37400|GPL
|50|CentralDesktop|34100|
%%

----

(Google and Alexa results from 14 Aug 2006) 
To every therm we added "wiki", eg. "MediaWiki wiki", "MoinMoin wiki" in an effort to exclude abiguous terms.

%%sortable
||#||__Wiki Engine__||__Google Res__||__Alexa Rank__||__License__||__Link__
|1|MediaWiki|295000000|9091|GPL2|[markup|http://meta.wikimedia.org/wiki/MediaWiki_User's_Guide:_Editing_overview]
|2|Twiki|4680000|22998|GPL
|3|TikiWiki|4130000|21130|LGPL
|4|PukiWiki|2510000|4850280|GPL2
|5|MoinMoin|2120000|58494|GPL
|6|PmWiki|1260000|31888|GPL
|7|DokuWiki|969000|556859|GPL2
|8|PhpWiki|913000|1398912|GPL
|9|MoniWiki*|861000|0|GPL
|10|TiddlyWiki|831000|92717|BSD
|11|JSPWiki|703000|92813|LGPL
|12|SnipSnap|580000|128718|GPL
|13|WackoWiki|369000|172554|BSD
|14|Xwiki|343000|184037|LGPL
|15|UseMod|282000|87300|GPL
|16|Midgard Wiki*|230000|89949|LGPL
|17|FlexWiki|220000|167955|CPL
|18|Instiki|216000|140083|GPL
|19|Zwiki|209000|174086|GPL
|20|TracWiki*|206000|87279|Mod. BSD
%%

 * Engine does not have its own domain name, so Alexa rank for this wiki is misleading.

!! Commercial Wiki Engine Popularity
(Google and Alexa results from 14 Aug 2006)

%%sortable
||#||__Wiki Engine__||__Google Res__||__Alexa Rank__||__Markup__
|1|Confluence|4580000|8652|Yes
|2|JotSpot|2300000|4850|No
|3|PBwiki|1920000|5205|Yes
|4|Socialtext|993000|50754|Yes
|5|SamePage|422000|405443|No
|6|Wetpaint|257000|10987|No
|7|Wikispaces|227000|13200|Yes
|8|SeedWiki|164000|20878|No
|9|EditMe|110000|43845|No
|10|StikiPad|109000|33897|Yes
%%