Useful Websites

Some websites/pages I find useful

Mapping

OpenStreetMap - The most detailed online map for walking/cycling
Ride with GPS - Easy route planning for cycling or walking, uses OpenStreetMap
FlightRadar24 - Plane tracker
Time and Date (sun) - Sunset/Twilight tracker, includes nice graph to show changing daylight hours throughout the year
Project Mapping - A variety of railmaps, main focus on the UK but also a lot of worldwide maps
London Rail and Tube Services Map - The full map of London rail services, showing all operators

What Unicode Character is this? - Tells you the name and codes of Unicode characters, useful for finding hidden characters in a string
Pygments Example Code Files - Example files in every programming language in existance (probably), useful for testing syntax custom highlighting

Arch Wiki - One of the best resources for Linux "stuff", even if you don't use Arch

Passmark CPU Benchmark - Benchmarks for basically every CPU in existance, obviously one benchmark is not a perfect representitive of real world performance in various different tasks, but useful to get a quick idea how powerful a CPU is
Passmark GPU Benchmark - Same as above but for GPUs
Intel Quick Sync Video Wikipedia - Useful if you are buying a PC/CPU and want to check if certain video codecs have hardware decode/encode

GB Rail Rovers - Good list of rail rover tickets in the UK. Not sure how up to date it is
ProCyclingStats - Lightweight website showing lots of useful data about ongoing cycling races
Bike Gear Ratio Calculator - Calculator for bike gear ratios
Bike Tire Circumference Chart - Self explanatory, useful in combination with the above gear ratio calculator