A small collection of traits which I find helpful:
CachedModelTrait: Usually added to App to cache model records which are often used in read-only mode.
CryptIdTrait: Generate a cryptic ID for a model field like adfsdfkj2-f23ref-rwe in a custom format of your choice
UniqueFieldTrait: Check if a field of a model has a unique value across all model records.
EncryptedFieldTrait: Store the field value encrypted in Database.