The main use of Calvin is for asset spam. But it is still a good card anywhere else. The tempo gain with this asset is very good. One click, get two cards, fantastic. Even when it is trashed, you get the effect.
And with only 1 influence, you can splash it anywhere. Litterally any deck is better with it. Of course, Rashida Jaheem give an even better tempo boost. But Calvin does not trash after use. With this, you can litterally install two cards per turn without ever diminishing your hand.
This card pairs well with Divert Power, since it has a rez cost of 0. And with a cost of 3 to trash, it is a tough choice for runner, since the corp gain even more when the runner trash it, by creating a credit differential AND getting 2 cards.
This beg the question : why not use it in every deck. The answer is always the same : there is only so many card possible in a deck, otherwise, this is so good that it should be there nearly all the time.
Did I mention the wonderful art of the card. Sooo good.