Compressing webpages, built in mail, built in BitTorrent client, tab stacking, "fit to width" which would remove horizontal scrollbars, page tiling, mouse gestures, rocker gestures, I think it even had a calendar.
It's a shame the direction Opera took after Jon left, but thankfully he started Vivaldi which feels like the spiritual successor.
Flash and Java, honestly, albeit in different ways. Both saw the web as a platform above all platforms.
Flash was the only way for browsers to do anything high-performance or good-looking from like 1997 to 2010. Any idiot could slap together a cool spinning animation with gradient-colored vector graphics. There were countless genuinely-free games, apparently made for the fun of making them, and even more interactive animations, apparently made to be as offensive as humanly possible.
Java was the big-grey-rectangle alternative, where you knew your browser was about to spend five entire minutes loading something, just to demonstrate a bouncing ball experiment or whatever. But: it was a real general-purpose executable format, with no installation or setup. You stuck a program on a page and it worked right there on the page. Eventually. And once it loaded it'd hitch and jerk constantly, because garbage-collection was always a terrible idea. But sometimes you'd find a page that'd hitch and jerk through playing Quake 2 in your goddamn web browser.
What ultimately killed them was that Adobe is among the worst software companies in the world and Oracle is number one. Flash was a security nightmare. It was hacked together for impressive functionality, and then repackaged for ease of use, so it was about as exploit-hardened as a wet paper towel. The fact it ran poorly on phones (and Steve Jobs was a dick) was just the excuse to stop tolerating its endless vulnerabilities. Java meanwhile was an okay format owned by the devil. It served kinda the same role as WebAssembly does now, except absolutely no-one wanted to put up with licensing it, because Oracle likes to sue its competitors and fuckin' loves to sue its customers. The company name is an acronym for One Rich Asshole Called Larry Ellison. And if two devices running Java connect via wifi, he expects the air in-between them to be properly licensed. If the free software movement had not been founded to say "fuck printers," it would have sprung into being in order to say "fuck Oracle."
Anyway.
Google Chrome, intolerable leash that it now is, made Javascript usefully fast in 2008. Prior to that it was interpreted. Javascript calculators in the AOL days could lag. Mozilla responded with asm.js, inviting the language itself to be performant. Nowadays just about anything could be WASM + WebGPU, and quite frankly most things should be. But for some stupid reason even the chat programs written in Javascript bundle their own browser.
Excel enabled non-programmers to create basically any app as long as they are fine with a cell-based UI. Same with Access and CRUD apps. I know people love to dunk on M$ here, and for good reasons too, but these two programs are probably responsible for a decent chunk or PoC/v1 projects worldwide.
Nobody had enough bandwidth to actually stream anything. I guess some people had IDSN, and maybe even fewer cable internet, but the majority of the world was still on dial up. You can't stream video on dial up.
Google glasses, I think it's death was mainly because it looks nerdy aside of course the huge privacy concerns. Which honestly don't exist now. Look at twitch streamers streaming everywhere. People installing cameras at their home and connected to the net for the world to see. Now we are going hard with VR/AR even Apple has a product for it.
Kai's Power Tools in 1992 . The interface was so next level it felt out of place and the more you used it features would get unlocked and more advanced. https://winworldpc.com/product/kais-power-tools/20
Searching for almost anything was so much easy. Such a powerful tool that disappeared. Its performance 20 years ago was better than Finder is today. At least from my experience.
I'm gonna cheat a little one and mention the PSP GO (take it as an honorable mention because it uses software to work lol).
The damn thing was meant to be used with an online connection to get games, updates and DLCs but people failed to see the appeal to it (mostly because of the poor infrastructure we used to have) people decided that UMD was the better option and guess which of those thrived.
zmodem. It was the fastest way to move data back in the day and was a trailblazer for streaming protocols. It excelled over dialup connections. Moving a file by say ftp over tcp/ip was painful by comparison.
KeyKOS, EROS, and other capability-based mainframe OSes could offer security and data integrity guarantees that "modern" OSes are only now just catching up with. Nothing from the Unix or VMS lineages, including Linux and Windows¹, really comes close.
The next chance for widespread adoption of a capability-based system is maybe Fuchsia; if Google ever deploys it for anything other than Nest devices, or if its open-source core gets picked up by someone else.
¹ Windows isn't literally a VMS, but modern Windows descends from Windows NT, which was led by Dave Cutler, who had also been the tech lead on VMS. And there's the joke about "WNT" and "VMS".
It looked so good, and brought 64-bit computing to the mainstream. Everyone fucking hated it because the computers that they had (which at the time was the majority) absolutely sucked.
Superscape Do3D blew my mind back in the day. I used to spend weeks just building little houses and landscapes, then watch them come alive with virtual "NPCs" and such.
Definitely required some imagination, but for a time when connecting to the internet still made a noise, it was definitely impressive.
I remember when Minecraft was first being developed, my first thought was that it looked like a modern voxel-based Do3D.
Here's a full GUI vector graphics/word processor/productivity app suite with clean Motif-esque decor and solid multitasking...
and it runs on a 512k machine with a 5MHz CPU.
The C64 predecessor was impressive too, but straddles the other side of toy/professional IMO.