You're probably thinking what an earth ear stretching is, right? Well, its not as extreme as it sounds…an existing ear lobe piercing that is gradually stretched to the wanted size.
Some may say it looks disgusting or odd but generally it's only ever done in the UK by the 'Goth' and 'Emo' types (who obviously don't mind looking out of place). Ear stretching originates from African tribes. They believed and still do, that stretching their ears will increase their perceived beauty.
How far can you stretch upto?
That's up to you and your ears. Most people tend to stop before or at around 0 gauge. (8mm)
How long does it take to heal?
It takes at the least one month to heal properly (if you just went up one gauge). To be safe, wait two months before you next stretch.
How?
Body piercing shops usually offer to stretch your ear for free, as long as you buy the flesh tube/plug from there. These can cost from £7-£15. Another option is to do it yourself.
You can use either a straight taper (either acrylic or metal, goes from your ending gauge down to the starting gauge), or a curved one. Tapers are also commonly known as insertion pins.
Another method would be to place a bit of Teflon tape around your existing jewellery, adding more the next day. This is unhygienic and can lead to the tape sticking in your ear. Yick.
Various sizes of tapers are available, but remember to only go up ONE size at a time. I find Ebay is best for buying them as it's cheap and has a wider variety. Also, the straight metal ones easier to use, and they can be sterilised easily to be used again. Jewellery needs to match the size of the biggest part of the taper. If you're worried about the pain, or a previous stretching has been unsuccessful, try taking a long hot shower before hand.
1)Wipe ear with antiseptic wipe
2)Simply slide the taper straight through your ear, for a second it might be painful but bearable, pretty much the same as getting your ears pierced for the first time.
3)Once you get to the end of the taper, place your jewellery up against the end so it looks like an extension of the taper, and push the taper the rest of the way through with the jewellery.
4)Wipe ear with antiseptic wipe
Your ear will feel like its burning for the next couple of hours or so and may appear slightly red, but that's normal.
If your ears are extremely sore or bleeding it means you have stretched too quickly! To be safe, take out the jewellery and replace with the previous. Treat it the same as a new stretch (wiping with tea tree oil, salt water etc). Wait 2-4 months to stretch again to avoid damaging the tissue.
Will my ears always be stretched?
The vague point of 'no return' is around 2 gauge (6mm) : becoming less likely to return to the size of a standard earring. This ultimately depends on the elasticity of your skin. The stretching will definitely shrink, but how much differs from person to person. If you gradually stretched its more likely that they will return to a normal size as scar tissue hasn't built up.
Aftercare
As already mentioned, salt water and tea tree oil are the best for helping them to heal. Dissolve around ½ a teaspoon of salt into 500ml of warm water - about shower temperature.
For healing stretching it's advised to wear glass, titanium or surgical steel jewellery only to prevent infection.
When it's healed, take the flesh tube/plug out for a few minutes every few days to relax your ear lobes. Don't worry, it won't heal up. I took mine out yesterday evening only to wake up this morning and realise I'd forgotten to put it back in - I last stretched a month ago and they went straight back in.
Vitamin E oil can be rubbed on to break down any scar tissue that is forming. Another reason for taking them out every so often is to clean the jewellery. Dead skin cells tend to build up on piercing, so again salt water can be used to clean it.
It can cost a lot to get to the size you want, but its definitely worth it. Don't take any shortcuts as they'll only back fire on you.
Useful links
Gauge chart. (Earrings are initially pierced at 18 gauge [1mm] )
http://jewelry.about.com/cs/identifyjewelry/l/blgaugechart.htm
Seeing the world through your ear...literally! 
Good review, but I don't know why people do it to themselves.