Just make sure you keep your Mturk password and your forum password different! Someone got my password for my email, and the only thing I've ever used that email for was this forum. Luckily I had a separate email for Mturk then I did here at the forum that is the only thing that saved me. So I logged in and changed my email. Good luck!
... Virtual keyboard would do you absolutely no good if you managed to install a Trojan on your pc as which can basically not only record keystrokes but can view exactly what you view on your screen, it's highly unlikely that your password was retrieved over your wifi, seeing how the attacker wouldn't just want your "mturkforum.com" account as that does really no good what so ever, If I were you I wouldn't log into any sites that aren't on your connection and or isn't your pc. Furthermore not that I think this is the case of someone sniffing over your wifi, you can always make your wifi more secure with changing your encryption from wep to something more advanced like wpa/wpa2 on your router settings. Install a good free antivirus like avast and keep it updated.
I don't share a wifi connection with anybody. mine is a standalone wireless broadband connection. Is my wireless broadband connection safe or prone to sniffing? I wish the smart hackers will better use their talents in making some good software like games and stuff instead of always trying to go for easy money. They are building up bad karma for themselves and they will rot in hell.