Totem should have a favorites list, or an interface to filtered (media only)
gnome favorites (if possible).  I choose to use Real Player over totem simply
for this reason at times.   The "open url" dropdown list doesn't preserve urls
between sessions.  I work around this by using the "Actions -> Run" dropdown
with saved entries like "totem mms://winmedia.whyy.org/live_radio".

The playlist seems to serve this purpose, but it is too easy to wipe out your
playlist and not easy enough to add items to a default playlist.