Could there be a way to see who has signed up for an event even while in game as well as to see who has not been approved but signed up for an event and still invite them from the mod if needed?
Today you would need to use the mod Group Calendar. The only implementation issue is that it works in reverse. Instead of signing up on the web you sign up in game and then import the data file to the website. This requires that EVERYONE in your guild must be using the mod in order to sign up for events and see the scheduling.
Also, would it be possible to have another window that would show the item values for all items so that we dont have to alt tab out to look at them?
I'm not sure what the status of item values in GRSS are. It does know about them if they have been seen because if you loot and item that has been seen before it will popup with the value of that item defaulted in the box. I think the easiest suggestion here is that when you link and item that has been seen or recorded in your items database and broadcast a bid start that the mod should dip internally and just announce the cost of the item with the bid. I think a loot list would be a bit more complicated to use in game than most thing and would cause issues with Blizzards item link protection issues.