So you’re having a great time in Sydney and you want to call your friends back home to let them know what they’re missing. Before you pick up that phone, you might want to check out this nifty little world clock meeting planner.

Green indicates work hours in each city (so that’s a “Go”) while red shows the sleeping hours (“Stop”). For instance, if it’s 7 pm in Sydney, it’s only 4 am in Chicago — prime REM sleep!

Ok, so the real intention of this website is to help you plan a meeting anywhere in the world — thus the green for go — but it can come in pretty handy no matter what the reason. And, of course, there’s an app for that.

Do you have a great travel website or app that’s helping you navigate the city? Share it in the comment section.