[Sorry for the length of this two-post response]
> Is this a good site to listen online? http://websdr.org/
I don’t know. I’ve never tried it. What I had in mind were stations that are put online by the broadcasters themselves, and that can be received (crystal clear) by programs such as Windows Media Player, Realplayer, or VLC Media Player. Many sites contain long lists of links to such stations, and you can find them by googling “online radio stations”. Other terms such as “live radio” or “streaming radio” and the name of a country or city you wish to receive will usually produce plenty of results.
If I understand the http://websdr.org/ site correctly, what it’s doing is producing a net interface to actual shortwave radio receivers at the various server sites, and allowing you to tune in frequencies and hear what the radios receive there. An amazing concept. It’s a way of listening to shortwave radio on other people’s receivers. :-)
It does sound interesting, especially if you’re looking for odd signals that might show up on particular frequencies, rather than programs from the major broadcasters (which are probably best received with the programs I mentioned at the ordinary net streaming sites).
I didn’t try the site because it requires installing and enabling Java (in addition to JavaScript). My only possible concern would be security, though as far as I can see the site itself is legit. It passed a virus check by a couple of programs I use. I noticed that some of the individual receiver sites did too, but others are listed as unknown (probably because they haven’t been used enough to be checked by the major virus checkers).
My general impression is favorable, provided you wish to try odd frequencies and replicate real shortwave listening. You don’t need that site, though, just to hear lots of stations from all over the world. To do that, other lists of online stations will suffice (they provide clickable links that will play stations with the software I mentioned).