I mean, let's face it, sometimes you need a break from work -- especially when you hit, oh, hour four of a six-hour flight.
Netbooks notoriously lack the processing and video power to run current-generation games (unless you're talking about "casual" titles like Bejeweled, which work just fine). But when you think about it, they're nearly as powerful as the PCs of yesteryear -- and there are lots of great games from that, er, year.
For example, there's Deus Ex. It's a decade old, with graphics to show for it, but as CNET points out, "this 2000 action/stealth/RPG hybrid is still considered one of the greatest PC games ever made." It's available for $9.99 from download service Steam (an excellent source for netbook-friendly games).
Other worthwhile candidates include the adventure classic Syberia, the original Half-Life (one of my all-time faves), the Diablo-esque Torchlight (which actually has a "netbook mode" for optimized play), and the very excellent Peggle.
Know of any other games that are well-suited to netbooks? Name your favorites in the comments.