Our user has commented nicely about Yoxel Personal sync in this Basecamp Answers thread (see last comment)  https://answers.37signals.com/basecamp/2534-outlook-task-integration

Just want to add here that we can do the same now for Zoho Projects: http://yoxel.com/zoho-project-management.html  Huddle connector is also coming.

Plus, we’re testing our contacts sync for Highrise and Google app: http://yoxel.com/highrise-synchronization.html