I'm looking for something along the lines of Nsk 3480.
Currently I'm in the market for the same need (a small mATX case).
I'm almost sure that I won't go for another NSK3480 (I already have one), due to its not so good PSU, a really horrible/inhesistent cable management, an actual sub par drive mounting, and an annoying slightly insufficient internal dimensions (I mean just less than one inch, but no clearance at all around the mobo). Nevertheless I will even consider it again if Antec would start to sell it without the loud EarthWatt PSU.
AFAIK there are not several alternatives, with reference to the NSK3480 dimensions.
The few ones (I don't regard any case which has any dimension in excess of 15,3"/39cm) that I've found up to now are:
1) Aerocool QS-200, maybe a bit crap, aestetically "so and so", but affordable: for silencers an absolutely unknown wild card, but it may worth a try;
2) Chieftec Series 300A (models SD01B, CD01B, DB02B), it seems a decent case, available with or without a 355W PSU, several colors/faceplates, not widely available (in Europe, at least);
3) Cooler Master Elite 340 (unfortunately it's EOL), very similar to AeroCool one, with an a bit more "el cheapo"/ugly appearance (even if beauty is on the eye of the beholder) than the QS200's one, very affordable;
4) Silverstone Sugo SG03 and SG04, well looking aluminium jewels, they're pricey and they may only use low profile (82mm) CPU heatsinks (but there's plenty of space for videocards): old versions (non -F ones) still available are to be preferred, according to me;
5) Silverstone Temjin TJ08, an overrated copy of the a bit crappy CM E340, but with a beautiful aluminium faceplate and more than twice the price tag, it's one of SPCR favourites;
6) Techsolo TC-600, similar concept of TJ08 (I mean a crappy body with an alu fascia), terrible (for silencers) PSU, a bit expensive, may not use some tower heatsinks as it is slimmer than ordinary minitowers, and which I guess it's not widely available outside Europe.
Among the so called "cubes", the only one I like up to now is the Langear DA Box 100, which has plenty of space, but it's also expensive (anyway, I'd rather a mini tower than the cube format).