Two models I would immediately like to see in Model Garden:

[WideResNets] (very helpful for benchmarking purposes)
Any colorization model

I had worked on a Colorization model 9 in the past months with a collaborator. It gave decent results but we could not get the distributed training part right. We are up for collaborations! Our pipeline is pretty fast so far utilizing the best practices from tf.data and is fully compatible with TPUs.