This tip comes from Blake Lawson, of MissionaryAirfareSearch.com.
TRAVEL TIP: One of our missionaries uses vacuum-seal bags inside her carry-on bags. She insists the bags shrink down to a compact package when air is pulled out by a vacuum cleaner. It allows her to fit three times the amount of clothes in a carry-on than would otherwise be possible.
Blake’s information, in case you’re interested, is here: Blake Stiles Lawson, Founder, 877.634.1199, 770.436.1334, 770.928.2659 Fax. I don’t recall using this particular service, nor do I receive any benefit from mentioning. It’s here as a possibility.