SWISS ARMY KNIFE -- male, because even though it appears useful for a wide variety of work, it spends most of its time just opening bottles.
KIDNEYS -- female, because they always go to the bathroom in pairs.
TIRE -- male, because it goes bald and is often over-inflated.
HOT AIR BALLOON: male, because to get it to go anywhere, you have to light a fire under it . . . and, of course, there's the hot air part.
SPONGES -- female, because they are soft and squeezable and retain water.
WEB PAGE -- female, because it is always getting hit on.
SHOE -- male, because it is usually unpolished, with its tongue hanging out.
COPIER -- female, because once turned off, it takes a while to warm up -- because it is an effective reproductive device when the right buttons are pushed -- because it can wreak havoc when the wrong buttons are pushed.
ZIPLOC BAGS -- male, because they hold everything in, but you can always see right through them.
SUBWAY -- male, because it uses the same old lines to pick people up.
HAMMER -- male, because it hasn't evolved much over the last 5,000 years, but it's handy to have around.
REMOTE CONTROL -- Definitely female, because it gives men pleasure; he'd be lost without it, and while he doesn't always know the right buttons to push, he keeps trying.