A new predicion (because it has been a couple of years since the last one!) is this -
Parasites will start to make a comeback - They will be seen as part of a healthy body.
Here is the thinking that will emerge - Humanity has lived with parasites since the stone age - for example tapeworms - so we have evolved to co-exist and actually "help" each other -
Even if the evidence isnt there, I can see people deliberately going for some parasites because of the "health benefits" conferred by them. Sort of like how worms were considered good for dieting way back when.
I should qualify my prediction by saying that I dont suppose something like fleas or ticks will make a comeback however - just the internal stuff.

 

This isnt such a leap, but I am amazed the product hasnt taken off (I am not even sure if such a thing exists) -
There will be a device which links game playing (playstation etc) to exercise -
There will be some sort of timer, which is a slot-in card for a gaming console. When the time runs out, you cant play the console  any more until you add more minutes to your timer
You add minutes to the timer by doing exercise (perhaps the card slots into a device which you could attach to a bike)  - this means that time at the gaming console has to be "earned" with real exercise
Another similar alternative is an excercise bike which regulates a power supply - so you have to exercise to actually be powering your playstation, otherwise the power is cut off
I have been meaning to post this for a while, but since today I noticed this, its even closer to reality:
http://news.bbc.co.uk/2/hi/health/6656631.stm

I have been talkng about this for the last 5 years or so, so this one isnt really new
Much to my delight, it is proving to be a prediction which is coming true - 
Virtual meat - just as people grow skin in a petri dish for plastic surgery, I predict that meat will be grown in factories (instead of us raising animals and killing them). 
A humane (and cheaper) alternative to real meat

Its only a matter of time (15 years?) before someone takes one of plays written by virginia tech shooter Cho Seung-hui and performs it as a full production to a live audience
Perhaps his family refuse to allow it...

Its just a matter of time before outsourcing hits a new business model - retirement
It wont be very long before we are outsourcing our retirements to warmer, cheaper places- special communities with good medical coverage (putting people out to pasture)

In the future there will be pop-psychology hours spent on "the power of intonation" - the power of putting tone and enthusiasm into your voice -
Starving actors will be able to generate secondary income by teaching people how to make themselves appear more interesting and attractive entirely by manipulating the tone of their voice

I think an OPEC-like cartel will develop amoungst chocolate growers- Ok its not going to shake the whole world like an oil crises does, but it will still be economically significant -