Standard discounts from operators

ToneToni

Just wondering what standard discounts operators give to new customers joining their network on contract. So far i know of:

All Networks:

• Cashback from cashback sites if ordering online

Orange

• Handset buyback- Here orange give upto £50 cedit for an old functioning handset
• Recommend a friend- Here you get £25 airtime credit on your account and the person your referring gets £25 Can apply for this on their website
• £50 credit can sometimes be had if choosing an older handset
• Orange Family- If one or more members of your family have an orange account, you can combine the bills into one and receive 50% extra free calls a month
• Orange Student- 1000texts and 120 minutes (other tariffs available) for £25 a month- requires an NUS number or Uni letter.

I have yet to find out if all these offers can be used together.
If you know of anymore ways or have more information please add them to the list