I work with a team spread across Sydney, London, and SF. Last month I accidentally called my Aussie colleague at 3am their time during what I thought was a "quick sync". The silence before "mate... do you know what time it is here?" still haunts me.

Built this: https://timezig.com

It's a timezone converter but it tells you if your meeting time sucks for the other person: - Meeting quality ratings (excellent/good/fair/poor) - Visual indicators for day/night - Shows if it's a holiday in their country - Handles weird cases like Dubai's Sunday-Thursday workweek

Technical bit: pre-generated 18k+ static pages for every city combination. Loads instantly because there's no backend calculations. Next.js 15, no database.

Still figuring out monetization (ads? affiliate links for virtual meeting tools?) but keeping it free for now.

What else would make this useful? Currently tracking holidays for ~20 countries but could add more.