It would be useful to be able to format numbers to a fixed level of
significance. Just as we can now format a number to have a certain level of
precision (figures after the decimal point), it would be relevant to format
cells with a certain level of significant digits. Say you had the following
numbers:

12.34567789
1.99999999
101.456789
14.5555555

format to fixed precision (say 2 decimal places) currently gives:
12.35
2.00
101.46
14.56

(Note these have different sizes so in a table we need to accomodate all
cells to have the spacing of the largest number.)

format with fixed significant digits (say four) would give:
12.35
2.000
101.5
14.56

( and all cells would have the same size. )

For science, sig.figs are more relevant than fixed precision.

If we wanted to get *CRAZY* we could make gnumeric able to track
significant digits through a calcualtion so any cell would only contain the
significance level of the lowest value that it depended on. Say:

A1 is 12.34
A2 is 32
B1 is =A1/A2
C1 is 134.2234433
D1 is =B1*C1 formated with dependent sig.figs would give: 52 i.e. the value
of the calculation rounded to the lowest number of sig.figs in the
calculation. 

another crazy idea for the extend period. :-)

--adrian