The option to add a photo or a file would be useful as well.
Also @Mike van der Valk - the ability to add Lead/Deal data fields to Activities. i.e. data fields we have created to appear in the Deal page. Purpose being, so that the person assigned to the Activity can populate the data field there and then within the Activity, and it appears populated in the Deal page.
We are trying to use Workflow Automations to create a number of Activities automatically as a Deal moves through stages (replacing the need for Process Street checklists) - but we aren't there yet. Would be great to see a Checklists feature in Pipedrive, to avoid the need to set up many, many Activities in Workflow Automations. A Checklist template (with tasks in the checklist assigned to various people) could achieve the same thing and greatly help users visually see the tasks that need to be done in a particular order.