Negative Numbers/Units.

[astsbins]

I think it would be really nice to have the ability to be able to have the units for measurable to goals to be in units. Say for example may goal is to read 10 pages of a book. If i read 15 pages, great! I can put in 5. However, if say I only manage to read 5, it would be good to be able -5 instead of just 0.

[hunterwilhelm]

I too would also like negative numbers to track bad habits.

[nitobuendia]

Another use case: Tracking monetary quantities - e.g. tracking savings. You may save $X one day/week/month, but you may spend $Y from your savings.