Easy MD5 is a fast and easy way to generate an MD5 on the go. Currently Easy MD5 is at Version 3.
Simply select a file and an MD5 is generated. If a .MD5 file exists, it will be tested. If you wish to generate a .MD5 file, you can do that too.
You can download it from the android app store here.
Update 4/2012 This is now open source and hosted on GitHub. Check it out at my GitHub page.