It would be nice to be able to use an equivalent of HTML SUB and SUP in a text object, something like :

SUP : This text is sup
SUB : This text is sub

it would be useful in some situations like

Fractions : 15/100
Nominal Numbers : February 6th, 2008

A way to implement this functionality would be to be able to set a vertical offset for a portion of text. The user could set a smaller font size and offset it to have it higher or lower the line.