I might be unique in wanting this feature, but maybe I'm not alone. I often find myself buying a stack of comics and unfortunately can't sit down and read the 100+ that day, or even that week. Then the next month they pile up a bit further and a bit further until I have a very unorganized stack of unread comics.
This does, however, extend to sorted comics that I've already boxed away without reading to clean space.
What I'd like to propose is a "reading list", or even a "Read" checkbox next to individual issues in a collection. Once I've read it, I can place a check. That way I always know whether or not the comic in my hand is the next one on my plate or not.
It's infrequent, but I sometimes find myself re-reading an issue here and there because I wasn't sure which one I had put down last.
Seems a bit silly considering most people are probably very organized with their collections and the sorting thereof, but for me I would find a reading list very helpful.
Chad Allard commented
It's true that the comment box would be a viable option (because you can use it as a toggle if you will... If unread, it has a note. If read, remove the note. That would display an icon to associate whether or not I've read it. Unfortunately I've already put a bunch of notes in for signatures, special appearances, price justification, etc..
The other option, like you say, would be to just keep sorting them into different piles. Nothing is stopping me from having an "unread' pile, but this makes it a little difficult to manage what I've bought and haven't bought with my current system of having a "currently collecting" pile that I look through before heading to the LCS.
You know what would actually be the PERFECT solution to this? Having the ability to add a comic to multiple piles / categories. The ability to add a book to both an "unread" pile and "currently collecting" pile would be absolutely perfect.
It would also give me the ability to group everything into the "master pile" for quick stat totals and to make it truly a "master" pile.
I have several ideas of ways to solve your problem. You can keep the unread books in your master pile and as you read them you can file them away into their appropriate piles on CBR. Not a good option though if you have already started to store away books that you have not read. The other option I was thinking of is, when you look in your CBR piles, there is a comments box next to each comic that you can edit and fill in. You can use this box to make a note that you have read the comic. I personally use the comment box for my subscription books. I put the number of issues remaining in my subscription in that box so I will know how close I am till my subscription runs out.