We've been using http://acunote.com to manage our work queue. It's great for the planning phase, because you can nest stories. This makes it easy to outline an MVP within a given sprint.
Given that we are a startup, we frequently have to juggle multiple projects back and forth within a given time period. For example, this week we have to update a partner website, develop the backend for our main product, as both web, iOS and android clients. The three clients have different engineers working on them.
I would like to use a kanban board to visualize our current sprint. I find that they allow me to more easily see progress.
I don't know how to manage the fact that we have multiple clients. It seems like it would make it hard for our mobile guy to know which mobile tasks are remaining. They might not be next to each other.
I also like that we have little mini-MVPs within a given sprint. Normally, if we finish one, we can start working on the next one, but we want to get them released in between. They don't line up with sprint boundaries.
Should I use separate boards per mini-project? Per web/iOS/Android clients?
Is there a good digital kanban that allows you to order individual boards like a backlog?