Several times in the Time section I needed to locate an specific task or find tasks that are not connected to any project and there's no search box. Not sure if the search box is the real deal here, but I'm sure that these problems among others are not easy to solve at this moment.
First I would say that a task that is not connected to a project is dangerous situation that need to be very visible with some sort of alarm... user just know what has N tasks unconnected and alerts can be dismissed or solved but it is imperative to pay attention to it.
Usually I work for three or four clients during the week. I don't use the Task section, usually it is more operative to record the activity in the Time section. When I want to come back to a task I started a couple of days ago there's no way like a combo of "Last days tasks" where I can select the task I want to continue. By the way if I create something in the Time area it would be nice if there I can check something to convert it in a Task. In fact the Tasks section can't be filtered by time range like "Today" or "Last 7 days" because Creation Time is not a field (which is quite important to see) and the Projects combo is too big and slow to swtich among most recent active projects.
But well, if search box could a good option then to search by orphan tasks, by time range, project, user, content, time duration (less than 5 min, between 15 to 30 min, and so on), and combinations of them would be a good tool I think.