JDM von Weinberg , Jun 29, 2009; 11:25 a.m.
It would be a helpful start to actually measure the size of the negative. It's possible that what is "odd size" to you may be a standard format. Is it a black and white negative, or a color one (the latter will look orange, because of a mask built into the film)?
Finally, it's increasingly difficult to get old negatives printed anywhere. You might try taking it to a local camera store or even Walmart and see if they can send it off somewhere?