Last I knew, yahoo did not allow hotlinking. I didn't notice anything in
http://smartgroups.com that says you can't do it there. ASPHost and others aren't very dependable. The only one I know of that allows hotlinking without charge and is dependable is AOL. But, of course, you have to use them as your server.
The issue is that it eats up bandwidth, which is the main expense of running sites/hosts. Boomspeed will allow patriotic images to be hotlinked. But, you must have a paid membership account in order to hotlink anything else. It's not that expensive. But, when money is an issue, even a small fee can be prohibitive.
Your best bet is to do up some web pages with the images and just link to that. It's an extra step for folks, but easier than finding a host that allows hotlinking. One thing to keep in mind is that most hosts also don't allow file storing. So, if you put up images, do them on pages as a small site. That way, they'll allow it to stay. While there are a variety of "free" hosts out there, many don't allow adult content, have huge obscene banners and/or are unreliable. The best I've found so far is
http://cybehosts.com Unless they've hidden something more from me (as some sites do with their banners), all they have are simple text box banners at the top and bottom of each page rather than images.
Ann