Formula auditing tool like trace precedent/dependent are very helpful in tracing cell links in a big excel file.
There is one more trick which can make your formula auditing little easier and that is F9 key.
In a formula press F2 to to show the cell links, then select the particular cell address and press F9.
It will show you the value of the cell
If you select the formula within the formula of cell it will show its result.