Perhaps, this thread could become a list of specific suggestions. That way, even if they remain unimplemented, the information remains here to be discovered by users.
example:
Due to lack of photo of the underside of all Teensy with pins products, and lack of proper text description, I have several times regretted my decision to purchase a large batch of teensys with pins(should have ordered without pins) because I assumed that all of the bottom pads would also have pins. It does not. Only the outer, through hole positions have pins. All of the inner pads remain unpopulated. My intent was to use wires with female to female Dupont connectors to hook up Arduino shields to the bottom pads.
My recommendation is to add a photo to all Teensy with pins product pages depicting the underside of Teensy w/pins.
Also, for text browsers, add a note that only the outermost through hole pin positions are populated.
List all pjrc.com products that are incompatible with the Teensy w/pins. And on those product pages, note that they require Teensy without pins.
For example,
https://www.pjrc.com/store/wiz820_sd_adaptor.html makes no mention that because they require special top facing pins, it is incompatible with Teensys with pins.
I bought one of those for each of my Teensy with pins on the same order and was very disappointed when they arrived.
I was very impressed that Robin once caught the fact that I had ordered a Teensy 3.1 and
https://www.pjrc.com/store/sd_adaptor.html on the same order and warned me of the incompatibility. I made it work any way, but it would be nice if there was an automated script that checks items in your shopping cart and pops up a warning list of mutual incompatibilities before completing the purchase.
If possible, offer for sale surface mount pins to populate the bottom side pads.
The recent website split between 8 bit and 32 bit items is a very large step in the right direction. Old instructions with AVR specific registers referring simply to Teensy and not distinguishing between AVR and ARM products (because there were no ARM products at the time of writing) are very confusing to newbies in the current realm. A careful audit of these references is required.
The new pjrc.com main page with product links and recent blog posts is very much a step in the right direction. Thank you.