See my Wikimedia Commons user page:

I support on/off buttons for opt-in ads on a nonprofit Wikipedia for all readers (via cookies).

Note: To support integrated watchlists or opt-in ads please add the relevant userbox wikitext below to the top of your user page, your user talk page, etc..

{{User:Timeshifter/Userboxes/Integrated watchlists}}
{{User:Timeshifter/Userboxes/Optional ads 2}}

For more info see: