Move all the settings to admin/settings, too confusing to have some in view and some in settings and no telling whether the tab in Views will work in version 2 anyway.

Add custom Views fields builder to create caculated fields that can be added to any view. Build each one with a SQL snippet like (%MyField1 + %MyField2). The columnSUM, AVG, and COUNT totals can total both normal Views fields and these custom fields.

Mostly working, but may not be production-ready.

Rework module to do calculations in the db instead of in PHP. This is a starting point to be able to expand on the kinds of calculations it can do.

A module to add simple calculations to a views table. You can SUM, AVERAGE, or COUNT a selection of fields in a row, or perform the same calculations on selected columns. The calculations are added as additional table cells at the right and bottom of the table, and a plug in theme makes the view look more spreadsheet-like (right justifies numeric fields, shades calculated columns and rows, and underlines calculated rows.