Froot - based mainly on suggestions gleaned on here over the years this is what we do:
We have a pocket money book - i.e. no actual cash changes hands, but everything is written in the book - debits and credits. I'm a bit of a dragon re sweets, and they are only allowed to spend 20p per week on sweets. But in reality they only choose to do this about once a month anyway, as they are always saving up for something special. Also any cash they are given by doting relatives, or for birthdays and Christmas also goes in the book.
They usually spend their money on Lego or sometimes books.
In the past we have had 'grace' pocket money, and then additional bonuses for chores and/or behaviour targets.
In my mind I have a figure of 10p per year of age per week being a reasonable sum. (i.e. 50p and 70p for my boys - aged 5 and 7).
Atm we have pasta jars - discussed at length on other threads. At the beginning of the week they get 5 pieces of pasta in their jar. Theoretically during the week pasta can be removed from the jar, but in practice this very rarely happens in our house - the threat is enough. Then extra pasta can be earned by doing chores, or special behaviour targets. At the end of the week the pasta is ceremoniously counted up, and converted into money for the pocket money book at the rate of 5p per piece of pasta. (I know, I'm stingy!)
Sorry this was long - HTH