Display lag is that slight delay between something happening on a game console or a PC and that action showing up on screen. Finding a display with low lag times is important, so DisplayLag has a database you can filter by brand, lag time, screen size, refresh rate and more.
Admittedly, the site does muddy the terms "display lag" and "input lag". The former is a function of the display and the device connected to it, and the latter is a function of a user interacting with that device and what the display shows. The site's database is packed with display models from most major brands. You can use it to find the lag time for your current display or a display you're looking to purchase. If you're just curious about which display manufacturers and models have the lowest lag times, it can help you there too.
The site is just getting started, so it may be missing a few companies -- and with others, you'll have to look for the actual panel manufacturer's name, not necessarily the brand it's sold under. Still, it's worth a look before you go monitor shopping.
Input Lag Database [DisplayLag]