A quick browse through Newegg later,
Fractal Core 1000
Apevia xqpack3 or whatever crazy name it has, cube case
DIYPC Cuboid, another cube case
Silverstone PS08
Or
Any case, a couple hours, and a dremel tool. Any case can have great airflow if you chop enough stuff off the front, like I did to my $25 Rosewill FBM-01.