Harmless distractions like Angry Birds are perfectly acceptable browser game fodder, should you have nothing better to play, but a newly released port of emulator DOSbox for Google's Chrome browser is the superior option—especially if you love LucasArts adventure games.
NaClBox makes that possible. It's a newly released port of DOSbox—the free emulator used by the likes of id Software and LucasArts use for their classic MS-DOS re-releases (Wolfenstein 3D, Star Wars: Dark Forces) for modern day PCs. GOG.com uses DOSbox for its retro releases. Bethesda and 3D Realms recommend it too.
NaClBox takes advantage of Google Chrome's Native Client technology that lets developers host native applications in a browser. All it takes is a couple preference settings in Chrome, really. (Though, NaClBox's creators do warn of potential security and performance risks associate with enabling Native Client.)
And NaClBox works just fine, based on my experience playing games like The Secret of Monkey Island, Indiana Jones and the Fate of Atlantis and Sim City 2000 in Chrome. The emulator port's creators have demos of a handful of classic DOS titles available for testing at the official NaClBox site.
Ultimately, what NaClBox could mean for old school gaming enthusiasts is one more way—one easier way—to play proto-PC games from their browser or Chrome OS—which, by the way, is coming to Samsung hardware this summer.
Head over to the official NaClBox site to learn more, then give the emulator a whirl if you're interested. Just go easy on the guys' bandwidth, OK?