WiFi File Explorer Pro is free for one day from Amazon Appstore. Turn your Android phone into a mini Web server so you can download/upload file from/to it using a Web browser via WiFi.
Using this app, you don't need to use a micro USB cable or setup bluetooth pairing to transfer files between your Android phone and your PCs/laptops etc…
UPDATE:
Or, like timhn pointed out below, get File Expert free from Android Market (it is free and has many more features).
how does one add the amazon store to your device?