Keeping things simple we would have just used post-it notes and a whiteboard or wall. We have lots of concurrent projects and could have used up lots of walls.
But we also have remote clients, developers and testers.
So we decided on a software solution. This is what the OnTime Planning Board looks like with client names removed.
Of course it is all drag and drop.
Note that we are currently using 1 week sprints with two major releases for these types of projects. I have found that longer sprints make it hard for developers to estimate how much work they can accomplish in the time-frame as they are often involved in multiple projects. A week is just easier to see.
Going beyond the sticky notes: it is easy to sum up the amount of work assigned to a resource in a period of time as it is all dynamic; you can look at features/stories and manage defects; and you can also sort based on work flow steps priority, etc.
Overall the tool is helping us manage both agile and hybrid projects (scrumerfall) to suit client needs.
The trick with any of these tools is to focus on what you need it to do and not what it "can" do.