When I'm trawling around looking for tools, utilities and apps to do stuff, I usually spend a LONG time evaluating the alternatives to see what's the ebst. Sometimes I come across something cool that doesn't seem to be well known. This list is partly for me to remember where I got stuff from, and partly to help others to quickly find useful tools without needing to spend all the time I did.

Retro Stuff

Emulators

System	Name	Plusses
ZX Spectrum	RetroVirtualMachine	RVM is a very cool piece of kit. It doesn't just emulate the ZX Spectrum, it also emulates the Amstrad CPC, with more systems coming in future updates.
ZX Spectrum	Fuse	Although the "U" stands for "Unix", Fuse is a really good Spectrum emulator for Windows too. Fast, small, compatible and easy to use.
Atari ST	Hatari	Hatari may not be the prettiest ST emulator ever made, but it has caused me the least number of issues playing games, or doing DTP in TOS. It's solid, performant, and widely compatible.
BBC Micro & Master	BeebEm	A really easy to use, fully functional BBC emulator that's run everything I've thrown at it perfectly so far. Great for reliving those School Days playing Repton or Granny's Garden.
DOS/Win3.11	DosBox-X	DosBox-X is still being developed, unlike the standard 0.74 version which seems to have stagnated. DosBox-X features a nice menu, more options, and better Windows 3.11/95/98 support. Seems more compatible too.
Everything	MisterFPGA	The MiSTer project is a community effort to create a small device that replicates console and early (8-bit / 16-bit) computers via an FPGA in a relatively painless manner. A great site for MiSTer addons is MisterFPGA.co.uk

Development

System	Name	Plusses
ZX Spectrum	SpectNetIDE	Integrated into Visual Studio 2019, SpectNet provides some brilliant quality-of-life advancements over other Z80 assembler editors. Now also featuring Boreal ZX BASIC support, preprocessor commands, an in-built Emulator, and all sorts of goodness, it's my go-to place for Z80 development. Easily installable as a VS2019 component.
Interactive Fiction	Quest and Squiffy	Quest is brilliant for complex Text Adventures, while Squiffy is really easy to use for making page-based decision interactive fiction (like choose-your-own-adventure books used to be!).
Interactive Fiction	Adventuron	Adventuron is a superb system for creating online Interactive Fiction, including text adventures, page-based fiction and things like the choose-your-own adventure books.

Power User Stuff

Editors

Type	Name	Plusses
Editor	Notepad++	NP++ really is the best notepad replacement on Windows right now. With a landslide of plugins, fast editing of huge files, tabs and more, NP++ is great for anyone who needs to do a little more with their editor
Binary File Comparer	BAFFLE	Once upon a time there was a tool called CABLE on DOS. It was the best way to hack savegames or fix copy protection. Its successor, by the same author, BAFFLE, written in Java, is excellent for comparing binary files and making edits. Best of all, it's free.
Graph / tree editor	yED	This is a brilliant tool for creating state diagrams, process diagrams, trees, graphs and relationship diagrams. Chock full of neat features, I love it to bits.
Hex Editor	HxD	A very functional little hex editor that dynamically interprets the binary you're pointing at into a bunch of multi-byte types. Great for hacking binary files, looking for particular values and editing them.

Usability

Type	Name	Plusses
Start Button Replacement	Classic Shell	The Tiles thing in Windows 10 is flipping awful. Getting into your system settings, or finding an application quickly is just a terrible experience after you install more than a dozen apps. Classic Shell fixes the Start Menu to be just like Windows 95/XP/7, and makes it ridiculously easy to find apps, settings, control panels and more. Gets rid of all that Tile bollox and makes the Start Menu performant again.
Tidier Desktop	Fences	I have a LOT of icons on my desktop. As monitor sizes grow, and M$ keep making the start menu more and more crap, it's tempting to put icons on the desktop. Fences is a BRILLIANT app, well worth the money (Better when on sale via HumbleBundle). Organises icons into little regions.
Optimisation	CCleaner	CCleaner (for 'Crap Cleaner' to give it its proper title), is a great little app that can clear out temp folders, ditch cookies, but also reach into the Registry and remove unused links and DLL references that all slow down Windows. I've been using it for years with no ill-effects. Has kept my PC fast and slim for 10 years

Utilities

Type	Name	Details
DOS/Win9x/ME	ManMrk.Com	A great list of Boot Disks and utilities for DOS and early versions of Windows
DOS/Win9x/ME	PC-Tools.net	A great site with some nice little DOS and Windows utilities

Media

Graphics

Type	Name	Plusses
Editor	GIMP	I used to be a big Photoshop user in the early days when we got Student licenses, and the costs were low. In recent years, Adobe seem to think they have the monopoly on paint apps, completely oblivious that GiMP is only a short way behind in terms of functionality. Takes a little getting used to, and has its annoyances, but it's really very very good.
Make Animated GIFs	LiceCAP	I needed to capture an area of my screen and convert it into an animated GIF for uploading to Twitter. After much searching, LiceCAP turned out to be absolutely perfect.
Webcam Capture	YawCAM	The inbuilt Logitech webcam software is a bit rubbish sometimes. If you need to take hundreds of snaps for eBay, or stop-motion animation, YawCAM is a great little app to replace the bundled webcam image capture app.
Voxel Art	MagixaVoxel	MagicaVoxel is just amazing. The images you can make with it, the models you can quickly and easily build are mind-blowing. No prior modelling experience required. Just start painting cubes. Phenomenal app.

Sound

Type	Name	Plusses
CD Ripper	Audiograbber	I've been using Audiograbber for over a decade. Although it's not officially supported any more, it's just a perfect piece of software that does everything you need. It's fast, easy and with a little bit of config plugs into the new GNUDB service to auto-name all your tracks.
Audio Editor	Audacity	I think everyone knows Audacity. It's become the de facto Audio editing suite for those on a budget. It's got its quirks, but it's fast, easy to use, and packed with features.

Video

Type	Name	Plusses
Streaming / Recording	OBS	OBS is almost the standard desktop streaming appliance for Twitch streamers these days. It's fast, it's free and supports quite a few nice features. But it's also useful for recording chunks of your desktop, say for training videos, or capture a chunk from a Youtube video playing in a window. A bit of a learning curve, and can be quirky, but works nicely.