To customize the tips that show up, check out 'languages/en.php' for instructions.
@rjcalifornia I think there's already a plugin for that: http://community.elgg.org/plugins/820124/1.8.4/easy-adverts-18
But yeah, it goes randomly but it uses the php function mt_rand() so I guess you could build a better function for ads and use this :s
@Kimberly! Yeah, clickable links shouldn't be a problem.