Gem or fast way to build task management system

Hi,

I have built a platform connecting business consultants and information purchasers online using Ruby on Rails.

I wondering if there is any Gem to implement a task management service for business consultants, which is similar to basic version of Enterprise Resource Planning (ERP) system. A few examples of such features would include: registering client info, client case upload, client case status check, consulting service fee calculation, schedule check with calendar function, and other eDocs system.

If there is no such gem, can anyone recommend me a fast way to implement such system?

Thank you!

Taek