This is a good service if you would like to send a direct download link to a file you keep in Google Drive
Hosting a dedicated game server? Hosting a web server? Want to open up Microsoft's Remote Desktop protocol on your computer to the internet so you can connect remotely? FreeDNS (afraid.org) can help here. Create customized addresses that redirect to either IP addresses or other web URLs.
Downloads a high-quality mp3 file from a YouTube video. This is useful if you want to get a mp3 file for a song that's not on Spotify, to add yourself.
Use the iTunes album art downloader Ben Dodson created if you need to, say, manually add album art to a MP3 you downloaded off YouTube.
This website is a great little tool you can use to edit PDFs in some basic ways, including adding signing fields, adding form fields, and adding checkboxes.
The Google Docs of markdown editing. If you struggle to remember the notations you must use for creating markdown documents, this site is a great editor for you. It also supports saving your document as not only an .md file, but also as an .html file.
Canyouseeme.org is a great tool to check if you've correctly opened up a port, or even just to check if something is broadcasting on a certain port on your network.