Quoth Milen Dzhumerov on or about 2004-06-24:

I have made a logo of a project and now want to use it. But I want it to be 90x90 px and the borders to be a square. The logo now is very big and the size of the document is very big. Is there a way to automatically reduce the size to 90x90 or something near this and to place the object in the center vertically and horizontally.

If you're talking about when you export to PNG, there should be an option called "Bitmap size" on the export dialog where you can specify the height / width in DPI or pixels.

-trent