Bringing back a classic from last year: which fruits and veggies have the highest exposure to pesticides and therefore you should only consume the “organic” variety.
(this post was originally published in Nov 2014, and is back by popular demand).
It's really not debatable anymore: organic fruits and veggies trump non-organic ones any day of the week. On the one hand, organic produce has been shown to be much more nutrient dense and more bio-available nutrients when compared with non-organic ones.
On the other, and much more importantly: organic produce is not exposed to pesticides, which have the pesky habit of penetrating to the core of fruits and veggies we often purchase and eat. This is important because people often feel better about washing their produce well: while this may get rid of surface pesticides, it certainly doesn't do much to the pesticides embedded within the fruit or vegetable.
But let's face it: organic fruits and veggies are expensive and not always available. But there is a practical solution: not all fruits and vegetables absorb pesticides to the same extent. In fact, some (e.g. avocados) contain far less pesticides vs. other fruits.
You can find here a list of major fruits and veggies listed in descending order of pesticide content. My advice would be to buy only the organic varieties of the top 10-15 items on the list.