THINGS WE KNOW HACKERS WITH WPE PRO AND RPE CAN DO SO FAR!
Avatar reading
They are able to view your age and gender and user locale info (such as US) via information on your Yoville avatar, and also your Yocash/Yocoin amount as well as your player id
Send admin message to anyone
Simlar to the message you get when reported or when you log in they can send one like this to you, and also have creative choice over what message goes in there, but the message doesn't actually do anything
Filters
They are able to block certain actions directed against them, such as reports and kick attempts, so no matter how many times you try to do this action against them, it will do nothing. Things that they are probably able to filter are kicks, reports, trades, gifts and game requests
Screen freezing
They are also able to freeze the screen of anyone in sight, locking up your web browser, so that you need to shut it down and reload it (and this is ****ing annoying too)
It will usually do the same to them as well, unless they have filters to block it
Invisibility
After they activate it they will be invisible until you refresh by going out of the room and back in again, unless its set on repeating in which case they will still remain invisible
Adding to buddy list
They are able to add themselves to anyones buddy lists with a bit of work
Water baloon stream
They are able to throw water baloons in a stream like they're being fired out of a machine gun, this can slow the game down a lot when they do this..
Gifting stream
They are able to send gifts in a stream, similar to the water baloons, which when directed against yourself leaves you with little choice other than to refresh Yoville and go back into the game, (unless you have an autoclicker and can cancel requests quicker then they can send them (an option to open all gifts later would be helpful in countering this)
Trade streams
They are able to send multiple trade requests through over a short period of time, but if you keep cancelling and choose ignore all future trades you will be able to gain control again once you have cleared the backlog of requests
Buddy request streams
Similar kind of thing, decline then ignore future requests to get round it
New/old clothes/haircuts/costumes etc
Some of them do have a limited supply of these, such as some of the old hairstyles and the new ones too, and they can transfer these too
Store access
It seems they are sometimes able to get some items from the store with a bit of work, including unreleased items
Be wary about buying something that may be hacked though as Zynga have set traps before to catch people doing this
Jelly face
They will have a face that 'wobbles' along with the tops of their shoulders too, its fairly harmless if a little weird looking, it does make them harder to click on though( patched )
Clearing white boards
I think this is still possible for them to do with a bit of effort
Hiding under the screen
Still possible for them to do, and they're unclickable when doing this - usually
Maxing from games
They are able to earn 200 coins a day without actually playing through all the games
Badges
They are still able to boost badges to max out on them
Spinning like a helicopter
They can spin round on the spot but through various degrees of rotation, kind of like the cats and dogs do when they roll over( patched )
Kick anyone/anywhere -
Possible for them to do still, but takes a bit more effort for them to set up
Changing room layouts
They can make wallpaper display as flooring and vice versa in properties they own. They can also change room layouts of other peoples properties, the items will still be in their inventory though
Spamming messageboards
Can be done outside of their targets apartment, a bit daft though since they leave their player id when they do this, they need yours to make it work if outside your apartment, otherwise they can spam it from inside using the leave message box ( patched )
Reading PMs
They can also read private messages sent between other people, but not on the main Yoville screen itself
Casino odds
They may be able to obtain extra cash from the casino, but not a large amount in my opinion
Boosted stats
Boost the energy bar so they don't get the sandwich hanging there..