It would be great to reduce the use of "magic strings" when using the query/update builders. If there could be a new Builder<T> static types (like Query<T> and Update<T>) which would have methods similar to the following signature:

Query.EQ(Func<T, object> name, BsonValue value)

It could be used like this:
Query.EQ<Account>(a => a.Email, "test@test.com")