Mark as Unread::
This suggestion applies to private messages. I'm going to quote Nightingale here, since this feature came up in one of our discussions.

"Or you do like I do and you read the message on your phone. Think of a response. Then, when you get home on your computer you never respond. I really need a "mark as unread" button so I remember!"

I think she's right, that a "Mark as Unread" button would be useful. My problem is that I sometimes open messages while doing other things, and if it isn't important I close with the intent of replying later. Although, being me, I forget to do that sometimes and then the message gets buried in my inbox.

PM/Forum Leaving Page Warning::
This is a feature I desperately need so I hope it's taken into consideraton.
When typing a post in the forums or a reply in PMs I'll usually have multiple tabs open, especially if I'm referencing something in the message/post. When clicking back and forth between tabs sometimes I'll slip and click the Egg Logo or "Fantasy pet breeding game" sign, which then takes you to BK's homepage and anything you wrote on the last page is lost. A small pop-up notification box with something like "Are you sure you want to leave this page? Unsaved text will be lost." would help keep this from happening.

Fully supporting bothy of them.

The marked as unread would help when you dont or cant send a PM and it would be quite a nice reminder later.

The other idea would really be awesome specially when you have a big spill and then you accidently close or change the webpage like you said.

Support for both. Very useful for everyone I would imagine.

Yespleaseiwantthis.... Well, my reason is there and I'm sticking by that massive run-on sentence! I would find this feature very useful. I have lots of messages and they are buried fast!

I'll reply to simple questions or smaller messages on my phone. Anything larger than that however... Normally I wait because my phone doesn't use the message box so well (I can't scroll if my message becomes long). But I tend to read them so I can form a response.