Ability to derive the value of one custom field from others e.g. CF3=CF1+CF2
We recently launched updates to the Pivot table which allows you to create calculations on fields. With this new update, it would be possible to create a report which shows the sum of CF1 and CF2.
You can see more details here: http://blog.aha.io/index.php/pivot-table-calcuations/
However, based on current priorities, we are unlikely to make additional upgrades to derive value of custom fields based on other custom fields (from within a record itself). We hope you can understand.