What gets tracked gets improved. If you are not tracking your bugs, your bugs will only be fixed by accident. Many development shops use email, spreadsheets, or sticky notes as ad hoc bug tracking tools. These have poor visibility, poor communicability, and poor accountability.
PlayNicely - Beautiful bug tracking for software professionals
Simple Hosted Bug and Issue Tracking | Sifter
Project management, service and support, defect tracking, and asset management software : iTrack
Web-based (SaaS) Simple-ERP solution | WorkforceTrack