It's no sick joke: airline barf bags have become collectibles. Connoisseurs include a Berkeley technology professor, as well as a Massachusetts writer whose Web site, www.airsicknessbags.com , invites people to donate finds and become "patrons of puke." European and Asian airlines make their bags graphic-design showpieces—and for the best, fans have paid up to $220 on eBay. It's the yuck factor, of course, that's cool to kids. Pin your unused bags on a bulletin board to document your family's travels, or get gutsy and join the Web brigade. Swedish engineer (and dad of two) Rune Tapper displays his 615 samples (eight of them shown here) at www.sicksack.com . He has yet to secure fad nauseam's holy grail: a sick sack from the space shuttle.