I also read a good quote a while back. Went something along the lines of:-
"We are the biggest lenders to banks."
Unfortunately for us we cant set our own interest rates, effectively the money we have in our accounts is what they use to lend out to others, although its always sat there. Yet they give us 0.1% interest but charge us silly % for mortgages, loans, CC etc.. If everyone withdrew there money from there accounts, paid everything by post and got paid there wages in cash, I bet the banks wisen up.
I think there is a difference here mate of the 2 types.
Banks use our money that we deposit in our accounts to lend out money to other customers in the form of unsecured bank loans. They use our money in order to lend to other people at a higher rate of interest in doing so like you have said they give us a certain percentage back in the interest but more often than not its a very small amount.
The second type is where lenders such as Nationwide, Royal Bank Of Scotland, A&L, C&G etc etc lender from the Bank of England. The bank of england sets out what is known an the 'Bank of England Base Rate' as people are aware this forms the basis for which lenders lender money from the Bank of England in order to lend out Mortgage loans.
Now currently the bank of England Base rate is currently 5% so money is lent to these lenders in the form of a loan, sometimes the rate at which the Bank of England lends the money to these lenders also know as 'Libor' is lower than that of the 5%.
This is where most rates are formed when taking out mortgages as you will have Tracker rate, Discount rates, Libor Linked, Fixed SVR (Standard Variable Rates) these are all the different rates which really are formed from the bank of England base rate. Each product has different features which compliment them and have advantages as well as disadvantages.
The base rate forms the basis really for all the products that are offered by the lenders this in turn also effects the mortgage market as higher rates do not make it financially attractive to the first time buyer in for example the current market conditions.
I think majority of the panic in the current housing slump is down to people not accepting the fact that prices of houses can fall and so are therefore not selling as they still think they can achieve the same price as their original valuation. Once they find that the property has fallen in equity they simply dont want to sell and accept the fact.
People are renting out there properties to ride out the property slump.