One of the five Dell Streak leather cases just released by PDair is the horizontal pouch.
The $50 case features white cross-stitching, a magnetic closure, a rear pocket, and a cutout for the headphone jack. I can't do a full review due to time constraints right now, but I've taken a handful of photos that should be enough for you to get a feel for the case and decide if it's something you'd like for your Streak.
In lieu of a proper conclusion, I'll sum up my feelings about the pouch by saying that it works better as a travel MID/tablet case than an everday phone case. I actually bought it for the former purpose, as I was looking for something well padded that I could put in carry-on luggage, and have been a fan of PDair pouches for quite some time now. One of the company's playthrough cases or slimmer pouches (this is rather thick because of the flap) may be a better choice for someone looking for a daily-use Streak case, but for my purposes, I'm pleased with this one.
I could live without the cutout, though.
The PDair leather horizontal pouch for the Dell Streak is available now for $50.