Hi Peeps

I've just put in a order for a brand new imac desktop which comes witha 27"monitor, now even tho this is a huge high quality, I know from work experience the benefit of having a second monitor. Can anybody reccommend a good quality 2nd monitor to compliment my imac screen? And also where are the best (bargin) places to shop online/offline for 2nd screens that are good quality but cheap?