iWork Numbers is a spreadsheet program and is most similar to MS Excel NOT MS Money. You can make a simple ledger using Numbers where you enter the data and enter formulas to perform the mathematical operations to keep the balance up-to-date.
You can make a table where:
Once column is, for example, "Transaction Date", the next is "Type", the next is "Deposit", the next is "Withdrawl", and finally the "Current Balance"
"Current Balance" is the sum of the previous "Current Balance" + "Desposit" - "Withdrawl"
Here is my quick example:

F2=D2-E2
F3=F2+D3-E3
You can fill F2 down (to make the balance auto update for those rows) by grabbing the little circle at the bottom right of cell F3 and dragging straight down to fill the remaining cells of that column.