Chuck the mascara (every time you use mascara and push the wand back into the tube, it takes oxygen into the tube with it. And with oxygen, any bacteria that have got in there will thrive. So technically, you should chuck mascara every three months.) The eye-shadow should be fine if it's a powdery one (not a bacteria-friendly medium) but if it's a gloopy cream texture, better bin it.
Other things that don't last so well include lip gloss (that bacteria-laden brush going back into the tube, again) and those under-eye-shadow corrector pens with a brush tip have a habit of going smelly within a few months. Foundations should last 12-18 months, and lipsticks, two or three years.