Unfortunately, a lot of those recommendations will come from people who don't really understand (or didn't bother to read) the requirements and will simply suggest one of their favourites or merely parrot what they heard from someone else who might have read a review once.
For studio/mixing, you want headphones with a relatively flat frequency response, and isolation if you don't have a quiet environment. You don't want emphasis on any part of the spectrum because then your mix levels will be inverted from what you actually want. The standards here (that I have experience with) are the Sony MDR-V6, Sennheiser HD280, AKG K240 and M-Audio Q40. The V6 and HD280 are quite flat, the K240 has a bit of a midrange bump, the Q40 is strong in the bass but slopes gently. Oh there's the Shure 440/840 too which are ok, and the omnipresent M50 which I don't like and are a bit too wobbly for studio work, but people will recommend them anyways.
Also keep in mind that each person has specific frequency responses tuned to their own ear. Here's a popular test to find out more: http://www.phys.unsw.edu.au/jw/hearing.html
Keep that in mind when determining headphone response as well as how you interpret your mixes.
For DJ'ing, you really don't care about sound quality. Your primary needs are durability and isolation, with pronounced highs and lows so you can hear your beat cues over the noise. If your studio cans have good isolation, you can use them here as well.
For "fun" headphones, go with whatever the heck you like.
Your local music center should have a lot of headphones for you to try out.