Yes MMTTY is a good soundcard decoder for RTTY, the web page at:http://www.qsl.net/mmhamsoft/mmtty/index.html
Not a lot of RTTY activity these days, most old RTTYer's have switched to PSK31 for the most part.
Calling frequencies for RTTY are at the "080" on HF (14.080 etc.) tune between "080 and "090" you might hear some signals. On 30 meters tune around 10.142 or so. RTTY contest weekends is when you will find the most activity. But for general contacts you will find most on PSK31, around "070" on 40, 20, 15, and 28.120 on 10 meters and 10.140 on 30 meters.
Other digital mode software can be found at: http://www.digitalham.net/
The most popular is DigiPan, "most" of the software is freeware.
Hope tto see you on PSK31 soon.