If that's the case, it's Account Rollup to the rescue. In Account Rollup you can specify that you want 2 columns. That one column should be Actual and another Budget. When you select a budget column, you also select which budget you want to use.
From there, simply select the accounts you want using any of your segments or segment value combinations. Revenue for one account across all segments? no problem. Revenue for one segment across all natural accounts? sure.
To be clear, you can compare multiple budgets, perform calculations, compare to last year, etc. I continue to be amazed at both the uses for Account Rollup and the number of people who don't know it's in the product. For more info, there's also my original post on using Account Rollup.
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