The users page in Ask Ubuntu main page goes up to page 3988 and with about 36 users per page, that goes to about 143K users.
In meta, the users page only goes up to page 442 coming to about 16K users.
So, how can we get more main Ask Ubuntu users to come to meta?
It's basically for better main site management, raising issues that affect the main site and general info concerning how to 'behave' in Ask Ubuntu - how to ask questions, how to answer, community issues, etc.
Examples of questions that require the 'attention' of a larger audience:
What's wrong, Ask Ubuntu?: Low Voter Count
Community Promotion Ads - 2014
newbie User ask and GO away forever
Unanswered questions - what to do?
2014 Community Moderator Election
Feel free to edit this question to give more info and examples
I have designed a meta.askubuntu.com ad that can be used in the main site to advertise meta. Check it below and if you like it, vote for it at http://meta.askubuntu.com/a/8426/163331
Am not sure whether 'customize Ask Ubuntu' is the correct/perfect tagline there but it's changeable all the same.
I have added a grayscale and a color version of the image in response to @Braiam