Yes, they are many.
The best one (for me) and the one I almost always use is HouseCall from TrendMicro: http://housecall.trendmicro.com/
There are also online antivirus from Norton, Panda, ESET and other known antivirus software.
There's also http://safety.live.com . I've found this to be very good to use and it is given for free by Microsoft. Though if you can, I still recommend at least installing Free antivirus with realtime monitoring.