Cool. I suggest you simply do a 'Find All' search (Cntl + F) on OFFSET and INDIRECT etc within your worksheet and see how may hits you get. Make sure you select 'within workbook' and 'look in formulas' and then hit the 'Find All' option.
The other thing to look out for is that you are not copying large ranges throughout the worksheet. For instance, the other day I saw a spreadsheet that copied a big table of around 15000 rows times 11 columns to multiple places throughout the workbook without good reason. In all, there were 1.4 million formulas involved in duplicating that block throughout the spreadsheet, for no good reason. I restructured it so that aggregation formulas (e.g. SUMIF, SUMPRODUCT etc) were pointed directly at the raw data.
Some other things to check:
* you say you have lots of VLOOKUPS. VLOOKUPS are MUCH MUCH faster if your data is sorted, and you set the last argument to TRUE (although you need to read http://fastexcel.wordpress.com/2012/03/29/vlookup-tricks-why-2-vlookups-are-better-than-1-vlookup/ for more info and some gotchas).
* If you use SUMPRODUCT a lot, see if you can replace them with SUMIFS (new to EXcel 2007) because its faster.
* Don't use =IF(ISERROR(SomeFormula), SomeOtherFormula, SomeFormula), because both branches of the IF get evaluated even if only one of them is ultimately used. Instead, use the new IFERROR function. =IFERROR(SomeFormula,SomeOtherFormula). It's much simpler, and only requires half the amount of processing.
* Don't use IF statements like =IF(F1=0,"",F1) to replace zeros with blanks, because this suppression requires significant overhead to do something that you can accomplish with no overhead whatsoever via custom number formats.
So instead of something like this:
=IF(F1=0,"",F1)
… we could just use this:
= F1
…in conjunction with the following custom number format:
#,##0.0;- #,##0.0;;
Do a google search on Custom Number Formats for more info, or check out http://peltiertech.com/Excel/NumberFormats.html or http://www.corality.com/tutorials/custom-number-formats-excel
And finally, read and reread that link above (i.e. http://msdn.microsoft.com/en-us/library/office/ff726673%28v=office.14%29.aspx ).
Post back if you have any more questions.
Good luck