I make heavy use the Comment field in PostgreSQL. Most IDE's allow you to order by the Comment field in addition to the usual fields (e.g. Column Name, Data Type, etc.).

I usually prefix the column Comment with some sort of number scheme, then order by the Comment field within my IDE; for example, 01 USERNAME, 02 USER EMAIL ADDRESS.

This allows me to add another column to the table months or years later, then just modify the prefix in the Comment fields to have the IDE present the columns in the order I want them to display for me and other developers.