Post information about websites or software that people deserve to know about.
A program that, once installed, lets you run a command in command prompt to download all images from a given link. It's compatible with pretty much every site I've tried it on, too. (Twitter, FurAffinity, e621, Inkbunny, Newgrounds, e-hentai, Pixiv, and surprisingly even Kemono.)
The main downside is that it's a python script run from command prompt, so to install it you need to install python (and in my case that didn't work so I needed to install it through Chocolatey, which is another python script that does… something?). Once it's installed, though, all you need to do is feed it a link and it just works.
Twitter Media Downloader (https://addons.mozilla.org/en-US/firefox/addon/tw-media-downloader
Firefox extension. Essentially an in-browser version of gallery-dl for just twitter specifically. Easier to install, and it has an actual HUD instead of using command-line. It also lets you download a user's LIKES too, not just their media or retweets.
rule34.xxx is one of the few sites gallery-dl doesn't work on, so I use this instead. Lets you download the entirety of the results of a specified search.
Awesome Duplicate Photo Finder (http://www.duplicate-finder.com/photo.html
This program scans a given folder (including subfolders) for duplicates, then lists them and gives you the option to move or delete them. This is really useful for doing a first-pass over a mass-downloaded gallery before sorting it "properly" afterwards.