When you watch group info you can see which series they have worked on.
It would be nice if I could see which of these series are already on my lists.
There are certain scanlation groups from whom I try to read all series they are working on (though not necessarily on a daily basis)
So if a series is on a completed list, show the green check sign in front of the series name, so I won't have to check this series anymore.
In this way I can periodically check series from scanlation groups that are not on any of my lists.

I hope Baka-Updates implements that idea.

Are you talking about showing list status on the group page? For example:

http://www.mangaupdates.com/groups.html?id=1994

yea, the series list at the bottom of the group page.

i remember most of the series names that I've read, but for stuff like oneshots that end really fast you usually don't get a big impression and so you forget the names. if you implement the list status on the group page it would really save some time =)

exactly 😎