Good idea. It sounds like we have a few basic types of solution:
1. PC-based systems with USB or serial readers attached to the computer.
2. Microcontroller-based systems supporting multiple Wiegand or other readers, with or without a central database.
3. Network-based distributed systems with a centralized database and small uC hardware at each door.
Each has advantages and disadvantages, and we can write a FAQ to help spaces compare options. I am in favor of standardizing serial or Ethernet protocol for the auth databases, and making the uC code more uniform (i.e. functions for local database storing hashes, alarm system functions, etc.) when possible.
Arclight