I'd like to be able to specify if I did the gravity reading with a hydrometer or refractometer. The reason for that is that while the hydrometer value will drop during fermentation (alcohol is lighter than water and sugar levels decrease) the refraction for alcohol acually works against the reduction due lower sugars - so a refractometer reading when fermenation has begun needs to be calculated against the OG to get a meaningful value.
Re: Refractometer log entry This has been recommended in several others places. It is moving its way to the top of the list. I'll cross reference this with the others.
Refractometer support is live! It is a new gravity unit option on the brew log entry screen. Related post and spreadsheet about how to determine your wort correction factor: http://www.brewersfriend.com/how-to-det ... on-factor/