How about an exportable csv (or html if it is easier) that includes all actual and budget transactions - with identical columns (account, period, amount, etc). Include a column to distinguish between 'actual' and 'budget'. In this way, the user could pull the data into an Excel pivot table and easily perform ad hoc analysis on any combination of periods and/or accounts.
Ed
How about an exportable csv (or html if it is easier) that includes all actual and budget transactions - with identical columns (account, period, amount, etc). Include a column to distinguish between 'actual' and 'budget'. In this way, the user could pull the data into an Excel pivot table and easily perform ad hoc analysis on any combination of periods and/or accounts.