I have multiple projects set up in Todoist and often want to see tasks related to a few (but not all) of my projects. Is there a way to filter by projects in addition to filtering by tasks?
Unfortunately, that's not possible right now, but we may consider adding such option in the future. You're welcome to vote for this request in our Votebox: http://todoist.com/Vote/showProposal/49/
For now, as a workaround, you could use labels as contexts and this would allow you to search for a particular label.