I've seen something similar posted before, but what I feel is needed for my players more than just about anything is a better way for them to access shops and buy supplies.  As a GM one of the most annoying aspects of running the game is keeping track of every merchants wares, prices, and stock which has led to the aspect of my games often getting pushed to the back burner. I can envision it as a relatively simple system. Just like you can create a new character and choose to make it a pc or npc, there should be another option to make them a shop. Players should be able to click on the token or find the shop in their journals and see the merchants current inventory and prices. There could be a setting allowing players to trade automatically within the character sheet, or allow the GM to turn off that setting if they want more manual control. The items in stock could run on a system similar to Lay on Hands for Paladins or Action Surge for Fighters where there is a set maximum of that item and once they're out, they're out. It could also reset automatically on a long rest similar to those abilities. GMs should be given the ability to set stock and prices manually if desired. Selecting an inventory could be done by drag and dropping items from the compendium as is already the feature. Extra bonus points if a system was implemented where merchants could just be given a random assortment of wares/prices with the click of a button by the GM, with even more bonus points if these random wares could be filtered by item type/rarity etc.  I imagine the money management could be made fairly automatic as well, although I think the system would be fine without this. However, it would be a cool bonus if players could build a sort of "cart" and when they go to check out the money is automatically removed from their character sheet. Another cool feature would be to have a setting allowing the GM to choose whether or not players could sell items to specific merchants. Finally, a check box or something that allows a GM to mark an item as rare or limited time only or something along those lines meaning it would not be restocked once it was sold could be a cool way for players to see that an item is... well special and encourage them to buy it before its gone.   Any way, if you got this far, thank you for your time. These features being added would enhance the enjoyment factors that I and my players receive from the game, and I hope that others agree.