I have found Maybelline Full 'N Soft Mascara to be the least irritating mascara I've ever used. It's great for my extremely sensitive eyes because it has a very smooth, inky kind of texture that never makes your lashes feel stiff or tight. Maybelline says it has an ingredient that allows for easy removal, thus reducing the loss of lashes that can happen when mascara just won't come off. Its thick, bristly brush deposits a lot of color onto the lash line, creating the illusion of thickness. It looks really good if you comb through your lashes first, add a coat or two (while still wet), and wear a lot of dramatic black eyeliner (my fave!).
It is also available in a waterproof formula--however, because I have such problems with mascara, I've stuck with the regular kind. And let me warn you, it is extremely not waterproof. Any rubbing or crying will make it come right off--but hey, I think it's worth it. I just won't wear it to the beach. :)
Cost: Very affordable, and available nearly everywhere.
Good for sensitive eyes?: Definitely. This mascara keeps your lashes soft, doesn't flake at all, and comes off easily.
Looks?: Hot. Adds a lot of sultry thickness to your eyelashes.
Repeat offender?: Oh yeah. I've bought this stuff for years.