There are now a number of places on the internet where one can find and operate on-line software defined radios (SDRs). For a list of these go to http://www.websdr.org/. One of the best, now streaming 7 different bands, is http://websdr.ewi.utwente.nl:8901/ which is located at Twente in The Netherlands. I have used this one to hear my QRP signals on 40m from the UK. There is a very slight delay but I was able to hear my 400mW signal very well. Another has a recording of the 23cms band during an ARRL EME (moonbounce) contest using a 25m dish: you can tune the band and hear some amazingly strong CW QSOs via the moon.