Colour, colour, and yes, even more colour

Life in an apartment building - how BLAH! I love lots of bright colour and I can't paint my walls! I've come up with some great ideas to infuse colour into the place: bright n' happy yellow curtains that I painted with butterflies for the kitchen, buying unfinished wooden shelving units (they're SO cheap!)and staining them with colourful wood stains, throw rugs, big bright prints, slip covers for the couch - I'm even making a new lampshade out of bright beads for a funky lamp/endtable I bought at the Salvation Army in Montreal over Christmas! But our living room is HUGE, and the white walls just dominate the place, and make it seem so cold, when what I want is Mexico-warm. I love orangy-terra cotta, yellow, soft turquoise, rusty reds - in short, anything that reminds me of cacti, guacamole, and tequila :)

Does anyone have any ideas on how I can creatively (and cheaply!) infuse some colour into the room without painting the walls?

Thanks guys!
pisces