Hi Pinkbeauty! Nars Concealer works well for lips. It will give you the coverage you need without drying out your lips. First prime your lips with a lip moisturizer. After it absorbs, dot the concealer on the center of your lips and blend out.
I'm not sure if this is along the lines of what you're looking for, but Benefit makes a great lip primer called Lip Plump. It's nude colored, like a concealer, but made for your lips: http://www.sephora.com/browse/product.jhtml?id=P12
It provides a great base for other lip colors and is good at evening texture and color.
Worth noting: if you are wary of "plumping" products, rest assured that this does not contain any plumping agents (ie irritants, etc.) - it doesn't sting, burn, or actually "plump" at all -- it just means that it will make your lips appear more full.
Answered[ Edited ]
I don't know if this is the kind of concealer you're talking about, but if you're looking for something to cancel out the color, for me, I like to actually use a tinted moisturizer! It works better than any concealer for me. Concealers always really dry out my lips, and moisturized and healthy lips is a must for me. The tinted moisturizer cancels out the color (mostly) and it doesn't dry them out!
I hope this helps!
P.S. I use Covergirl Aqua CG Smoothers tinted moisturizer, btw.
Laura Geller used to have a fantastic lip concealer but unfortunately Sephora discontinued them. Out of Sephora stores, I would recommend MAC's ``Lip Erase``-- It's a fantastic product. Totally true to the product description.