Downloads

Apple

felixbruns.de / isoindex.com / ipsw.me - Sites hosting historical and current versions of Apple firmware for iPhone / iPod / iPad / Apple TV / etc.

Microsoft

Windows 11 at microsoft.com - Downloader and ISOs for Windows 11. Multiple versions and languages. Valid keys are required.

Windows 10 at microsoft.com - Downloader and ISOs for Windows 10. Multiple versions and languages. Valid keys are required.

Windows and Office at heidoc.net - ISOs for Windows and Office. Multiple versions and languages. Valid keys are required.

Networking

MAC Address and OUI Lookup - Media Access Control (MAC) address and vendor search

Software

"How do I create an .iso image?" - MacRumors forum post showing how to use Disk Utility and hdiutil to create ISO9660 compliant ISOs in OS X

Web Design and Web Tools

MXToolbox SuperTool - Look up nearly any DNS record

DNS Checker - Check DNS record propagation across the world

Microsoft Messsage Header Analyzer - Get insight into email headers

Web Safe Color Codes - A chart of all 216 of them

WhatTheFont - Upload an image file or specify a URL to get the name of a font

Jeffrey's EXIF Viewer - A nice web-based EXIF viewer

Devoth's HEX 2 RGBA Color Calculator - easily convert Hex vales to RGB/RGBA for CSS