Speck of dust on the view finder?

http://i.imgur.com/ScO​ee4G.jpg

I wiped the mirror and luckily it's not showing up on any photos... but does anybody know how to clean this?

You should not wipe the mirror, it is very easily damaged.
Your speck of dust is most likely on the focus screen, if it's on the bottom then it should be possible to blow it off with a rocket blower, do not use canned air and do not attempt to wipe the screen with anything.
It could be on top of the screen and if that is the case then it will need the screen to be taken out and cleaned. If you have never done this before then I would advise you to get it cleaned professionally.

The 6D screen is made to be removable and changeable by the user but it must not be touched with your hands, a special handling tool is supplied with new screens.

As it is only one little spot I would be inclined to leave it alone, it isn't going to make the slightest difference to your photos.

tnick771 wrote in post #18334989
Oh boy now I'm nervous I damaged the mirror. How could you tell?

If everything seems OK, then it probably is OK. Don't panic, the mirror is not as sensitive as some make it out to be. See http://davidcandlish.p​hotography …lr-mirror-focusing-screen and perhaps get a high quality brush for the future.

Just ignore it!

A while back a tiny spider took up residence in the viewfinder of my 1D4 - he/she provided hours of amusement when the wildlife didn't turn up! Disappeared after a while, I miss them