If you are not familiar with Collectible Geek, they provide two monthly boxes of collectible geeky items based on various themes. Just recently, they began offering subscriptions for one of their two boxes, but now you can subscribe to their ultimate collection!
The two box types are Collector's Cache and Build Your Own (BYO). You can also get the I Want It All collection (IWIA) and now both the Collector's Cache and IWIA have subscription options for three or six months. Collectible Geek differs from other subscription boxes in that it mainly is not subscription-based, but open by theme for the following month.
Here's a general breakdown of the system using January, February, and March for the example.
Mid-January: March's theme is announced (March will be Totally '80s).
February 1: All three March box options go on sale for anyone not already subscribing. When they sell out, they sell out (and they do within a week or so).
March 15: Boxes ship.