Simple Weight Tracker allows you to record weights, typically on a daily basis.
It has some space for notes and you can insert the current time into the notes.
The app is designed to work with Google Drive. It will save the weights into a comma delimited text file in your Drive account. (If you don't have a Drive account, you can send the file via email using the Share button.) From there you can import it into a spreadsheet and make charts.
I didn't originally intend this app to be published, so the name and location of the Drive file are not configurable. It's titled "LatestWeights.txt" and will be saved in the root folder.
The valid weight range is 0 - 500 with a .1 accuracy.