Your landlord says you can't paint. So what? There's tons of inspiring white interiors out there that add color through furniture choices. Embrace the blank canvas and invest in seating in your favorite shades. Best part is, they come with you when you move. You can't say that about the walls!
1. Mixing a pretty pink sofa with leathers and pattern adds interest and balances the feminine hue. Vintage Renewal via Houzz
2. A sunny yellow cushion highlights the structure of the chair and makes you happy when art is grey. Bright Bazaar
3. Chartreuse is a bold choice, but with a white backdrop, it doesn't overwhelm. Design*Sponge
4. Clean lines and an otherwise neutral palette makes the focus on the flirty floral. Rue Magazine
5. Possibly my favorite statement chair of the past few years, the CB2 Parlor chair in eye-popping DwellStudio fabric, I would gladly hand over my paint fan for this stunner.
MORE COLORFUL SOFAS ON APARTMENT THERAPY:
• Small Space Solution: Pick A Colorful (Try Orange!) Couch
• A Rainbow of Reasons to Add Colorful Furniture
• Bold, Bright Sofas: Rev Up Your Living Room
(Images: as linked above)
The Ultimate Used Furniture Cleaning Kit
Ana Creates a Community at Home
Good Food to Share 
The Big Book of Small, Cool Spaces 
Apartment Therapy Presents 
The Eight-Step Home Cure 
Z2 iPod Dock and Wi...
Soda Recipe: Homemade Ginger Ale
Recipe: Spring Fruit and Nut Tabouli
I like the way the bright yellow is applied to the chairs in the second photo. It's definitely there, but it's done in a more delicate way. I'd take the chairs in photo two over the one in photo five any day.
Sorry for this, but it really bothers me because I consider it basic english.
"There is a ton", or " there are tons". "There´s tons" is simply not correct.
Who makes that standing lamp next to the yellow chairs? Love these ideas! I do have to though a lot of people have that horrible tan/apartment off white to contend with and that would certainly be a design challenge. :)
Like the sofa in #1 but not the color scheme. Not much of a pink or pastel kind of gal. Really liked all the others. Those bold colors in 3,4, and 5 brought a smile to my face! Nicely done. :oD
@EuroMichelle, if you feel the need to correct someone's grammar, at least use proper form in your critique. You should have said "I consider it basic English," not "english."
Oh, and I LOVE that first image with the pink sofa and painted white brick wall. Unfortunately I'm too scared/indecisive to go for such a statement colour for the big, expensive pieces of furniture. I'm hunting for some more colourful patterned pillows and a rug to liven up my grey sofa.
@AESTHETICALLY INCLINED You should check these colorful rugs out! http://www.zinhome.com/turkish-patchwork-rugs/
I Love the chairs in picture # 4, image is taken from Ruemag. Where may I buy those chairs?
I love these ideas, but my rental walls aren't white - they're some kind of taupe/beige color. It's not a bad color, I just don't know how to deal with it. Ideas that would work with white walls won't work with this.
A great way to add a pop of color or pattern is to buy a painter's canvas and cover it with paint or with a colorful fabric you pin or staple to the canvas and hang on the wall.
I'm inspired by the patterned fabric on that final chair but usually I recommend a solid colored accent piece like a womb or egg chair replica from ManhattanHomeDesign.com