Interestingly, back when I was first playing around with Arc, I also thought the logo was odd. I designed a new one based around combining the letter A with the concept of an arch (http://www.paulgraham.com/arcfaq.html).
You can see my logo, with a favicon-sized image, here: http://imgur.com/a/RMGu4#sSFHTHt It uses the same colors as the existing one, and has the black border around the outside.
On the off chance anyone developing Arc sees it and wants to use it, that would be awesome, as long as it's properly licensed -- I'm not sure what the proper free license is for things that aren't code. Creative Commons withe the attribution and share-alike clauses? http://creativecommons.org/licenses/by-sa/4.0/
