***UPDATE***
So Santa (i.e., my sister-in-law) did in fact give me one of the Plan D tube fly boxes--the smaller one with the clear lid in the upper right of the photo flytie09 attached (Pocket Tube Plus). I don't have a camera so you'll have to work with my description.
Initial impressions: very well made piece of gear. Heavy gauge plastic, waterproof seal, one way vent. It comes with a bag of mandrels--basically, stainless steel pins with a hook at one en--that you slide through the tube fly and then press in to a slotted silicone block at either end of the box. You can trim the end of the mandrel to fit with a pair of wire cutters. The box comes with a set of medium mandrels; however, they're too big to fit my tube flies so I'll have to pick up a set of smaller ones (they come in small, medium, and large). There's a slotted foam block in the middle of the box that you can stick some trailer hooks in. The way it's configured you can't store the flies with hooks stuck in the tubes.
The box is 6 1/2 x 5 1/4 and a little over an inch thick. It holds up to 20 tube flies, is big enough to fit in my front wader pocket, but a little too big and heavy to carry around all day. That's okay--for wading and fishing I'll just stick a couple or three flies in an old aluminum cigar tube and the box can stay in my pack.
All in all it's a good piece of kit and a better storage system for my tube flies than the ratty old Plano box I was using. If you have and fish a lot of tubes I'd definitely recommend it, or one of the other tube fly boxes Plan D has. As I noted earlier I've also got one of their pocket size Intruder boxes (another Xmas gift from the sis-in-law) and it's a good design as well. It's hard to find dedicated boxes for tube and Intruder-type flies, but these Plan Ds fit the bill.
Scott