Resize Objects
Here is a script, (a pair of them really) that does something simple – alters the size of an object. This probably has some limited use, since it approaches the task by suggesting that you want to increase or decrease the size of an object by some mathematical factor. Yet, it still might get you somewhere in the ballpark, so that finer tuning is then possible by other means. You can also undo what you've done with this script, then run it again with a different factor, for another form of finetuning.
resizeobject.py
This first version asks for a single input for enlarging or shrinking. The default of 0.5 would halve the width and height. To double, enter 2. It seems to work on various kinds of frames, shapes, arcs, groups (a true group, not just a collection of selected objects), and even vector objects. Although it works on a spiral, there is a display problem after running the script, which seemingly can only be overcome by saving the file, closing, then reloading.