What is she?

I kind of agree with the boxer/dane mix.  She looks alot like one that comes to our park, just a bit smaller.

Is her coat short and kind of thick? She looks a bit thick-coated and long-snouted to be a Dane-Boxer mix. I almost wonder if she has some Rhodesian Ridgeback in her. Maybe some Blackmouth Cur? It can help to see what dogs are common in your area.

[linkhttp://www.dogbreedinfo.com/blackmouthcur.htm]Blackmouth Cur[/link]

Her fur is short yes, and I guess kinda thick.  I've thought maybe some rr as well.  I've never heard of the Blackmouthed Cur but it seems like a possiblity.  She seems to be pretty scent driven and will go crazy at squirrels on the other side of our fence and follow them tirelessly until she can't see them. On the otherhand, she's very gentle with our two cats (one being only 9 weeks old) but once in a while gives in to the urge to chase them if they pass by too quickly.  She is very vocal as well.  We live in minneapolis now but she was adopted in the Appleton/Oshkosh Wisconsin area.

My vote goes for Boxer x Labrador. Color and heavier jaws from the Boxer and coat and size and ear from the Lab. There COULD be Dane but I'd vote for 3 breeds not 2 if that were the case because once a Giant breed is mixed a couple of times they tend to get smaller but still stay over 50lbs.

I agree with the previous statements.

Keep in mind that just because she's part dane doesn't mean she'll get to be full dane size.  Genetics are silly, silly things and for that reason mutts can vary greatly in size and with other traits (even though some are more dominant than others). 

For instance, my puppy is a Giant Schnauzer/Standard poodle mix, and is barely 45 pounds right now (about the size of his mother, who's a poodle) and his brother is a little over 60 (much close to the size of the sire schnauzer).  Likewise, my dad's dog is a border collie/beagle mix who has the stature and hair length of a beagle with the size and color of a border collie, while his sister is the exact opposite (colorings and size of a beagle with long fur, proportionally long legs, and skinny).  And that is why mutts are biologically fabulous.

Alright, the bio grad student is going to shut up now.

[linkhttp://www.dogbreedinfo.com/boxadorphotos.htm]http://www.dogbreedinfo.com/boxadorphotos.htm[/link]
Looky at Duke on this page!

I would venture to say you have a Southern Black Mouth Cur on your hands. They are AWESOME dogs.
[linkhttp://www.blackmouthcur.com]www.blackmouthcur.com[/link]  In addition to the link jen posted.
They tend to be lean and around 60 - 90lbs. I cannot say enough about them.. I LOVE this BREED...
 
They also have bred a BMC with a Mastiff they are called BoreBulls, (the equivilant of a Pitty in the USA) in South Africa. Can you imagine a BMC attitude on steroids... lol
 
One way to tell if your girl is a SBMC is to look inside her mouth and look at the top of the roof of her mouth, is it solid black? And if she shows any of the traits in either link, then you have a SBMC. An AWESOME DOG!!!!!!!!!!
Most people think a BMC has the name because of the black mask they sport sometimes, however, that is not true. The inside of her mouth is the tell tail sign. They are also prone to double dew claws.
 
Either way, she is a BEAUTY !!!!

BoreBulls, the equivilant of a Pitty in the USA
 
Are you referring the South African Boerboel?
 

I would think lab/boxer as well with maybe some rindgback in there.  I don't really see Dane, her face just doen't seem to have that look.  Very possable there is more then two or three types of breeds mixed.

BoreBulls, the equivilant of a Pitty in the USA

Are you referring the South African Boerboel?
 
Ummm yep, that would be the one. I knew the name looked wrong to me sorry for the spelling errors.. Smack me!
 
That is what my uncle in SA has and uses his dog for is to take down hogs, and ............ that try to break into the home.

Wow rwbeagles that link of Duke definetly looks like Ezra with a little extra weight on her!  Forpaws, the roof of her mouth is solid black, but so is my other dog's. How common is that? I could possibly see some SBMC in her but her build seems a little off.  I'll try to find a better picture that shows her body.  Her chest is deeper and she has a very small waist.  Thanks for all of the guesses!

Kalisa that body style is VERY Boxer [] 
 
Mouth pigment is often tied to muzzle pigment or the color of the skin on top of the muzzle but not always. My Akita had a black roof as well....and  some random blueblack tongue spots lol!