The inverse of the Fisher Information: $Var(\hat{\theta}) \geq \frac{1}{I(\theta)}$.

The variance of the data: $Var(\hat{\theta}) \geq \sigma^2$.

The square root of the Fisher Information: $Var(\hat{\theta}) \geq \sqrt{I(\theta)}$.

The mean of the estimator: $Var(\hat{\theta}) \geq E[\hat{\theta}]$.