Jelly is a nice little ORM for Kohana. It is currently in beta.
Standard support for all of the common relationships — This includes
belongs_to, has_many, and many_to_many. Pretty much standard these
days.
Top-to-bottom table column aliasing – All references to database columns and tables are made via their aliased names and converted transparently, on the fly.
Active testing on MySQL and SQLite — All of the Jelly unit tests work 100% correctly on both MySQL, SQLite and PostgresSQL databases.
A built-in query builder — This features is a near direct port from Kohana's native ORM. I find its usage much simpler than Sprig's.
Extensible field architecture — All fields in a model are represented by
a Field_* class, which can be easily overridden and created for custom
needs. Additionally, fields can implement behaviors that let the model know
it has special ways of doing things.
No circular references — Fields are well-designed to prevent the infinite loop problem that sometimes plagues Sprig. It's even possible to have same-table child/parent references out of the box without intermediate models.