If you were anything like me, you burned away time in the computer labs by finding whatever Flash games hadn't been caught by the firewall yet. The good news is, some people share the nostalgia for that messy, beautiful era of game development, and have built an offline launcher of sorts to archive it for the foreseeable future.
Flashpoint is a preservation project for various webgames made in Flash, as well as in Shockwave and other formats. The project, as the developers put it, is "dedicated to preserving as many games and animations from these platforms as possible, so that they aren't lost to time." Run by a team called BlueMaxima, it's currently archived over 38,000 games and 2,400 animations.
If you missed the news, Adobe has been gradually killing support for the Flash platform, and many of these games could someday be subject to the whims of hosting platforms and other issues. As games get older, preserving them in playable states becomes an issue to tackle, and it seems like the BlueMaxima team has put itself up to the task of keeping this weird, wacky side of development alive.
You can either download the absolutely titanic Ultimate bundle with over 200GB of Flash content, or pull down the Infinity platform and download games as you play them. I fully recommend the latter option.
The master list already has some classics of my youth. There's the 3D Lego Studio Backlot game, and the historical autobattler precursor Age of War. A classic Bionicle adventure game set in the world of Mata Nui is fully playable offline, and there are a bunch of other Flash classics hidden away that you can sort into lists and browse, either in-client or through the master list. The developers are also taking requests, in case you don't see your personal favorite on the list, though the team is adhering to copyright claims and requests to not host games.
There are a lot of incredible games that offered free distractions to the lethargic youth of my generation, and I'm glad they're getting preserved. It's tough to think of time-wasters like Slime Volleyball in these terms, but keep in mind, gems like Frog Fractions and QWOP came from this burgeoning scene. You can grab the client via Flashpoint's site, and if you do, let me recommend the seemingly Zero Escape-inspired "No one has to die."