>Here’s a collection of good resources for finding logotypes, especially vector ones.
If you can’t find what you’re looking for, you can always use the old PDF trick of going to the corporate website and looking for annual reports or other documents where the logo is likely to be found. Then just open that page of the PDF in Adobe Illustrator or Photoshop.
If you still have no luck, do a Google search limiting the scope to a particular site, such as this: site:volvocars.com pdf
If all fails, you could probably find a bitmap of higher resolution in a PDF than on their site, usable for taking a screen shot of and perhaps trace.
brandsoftheworld.com (vector logos)
LaLogotheque.com (vector logos)
Beers (vector logos)
International Flags (vector, but remember to search for the French spelling of the country you’re looking for)
French road signs (vector)
Other signs (vector)
Apple illustrations (vector)
www.logotypes.ru (vector logos)
goodlogo.com (logos: bitmap and designer info)
Swedish Roadsigns (vector) and their typeface (TT)
cartype.com (bitmap logos)
Update 2006-07-13: here’s one more tip from AE Freemart:
stock.xchng (bitmap photos)