I will also be adding the Resource Friday posts to this blog. I think the format here is easier to search and the record of them will be better.
For this week I chose unitconversion.org. This website provides simultaneous conversion for numerical bases from binary (base 2) to base 36!
Keep in mind when using this that even though geocaching.com uses base 31 for it's GC numbers it is a modified version of base 31, and so will not match the conversion given here.