I subscribe to XM/Sirius satellite radio. I like it quite a bit, and I've been a listener for quite some time. In fact, I can't remember the last time that I listened to normal radio in my own car.
Here is one feature that I would personally use if they added it... a simple 'remember this song' button. Right now, as music is beamed down to my car radio, I can see the name and artist of the song being played on the display panel. And, often times, I really want to remember the song, because it's something new that I might want to hear more of. But, I clearly can't write anything down since I'm driving.
How nice it would be if I could just push a 'remember this song' button. And, based on my own preference, a compiled list will be sent to my e-mail once a week/twice a month/etc. The e-mail would not only include a list of the songs I've asked the system to remember, but it would also have some handy links that point me to where I could buy the songs or albums -- this feature would be something that XM/Sirius could monetize fairly easily.
It seems that when the radio is first turned on, it needs to make contact with the satellites to authorize. Why can't it simply send another buffer of data (songs to be remembered from my most recent trip) that was stored locally. Sure, we'd be lagging by a single trip, but that's better than nothing.
So, XM/Sirius people... get on this. But, remember not to charge extra for this feature, as few if any would find enough value in it to pay extra... just monetize by sending me links to purchase the music.