Here is a list of SAP certified third party add-ons to Business One:

Architecture, Engineering and Construction(AEC)
Addon Name	Scenario
Corecon 2006	Handling estmating, project management and accounting

Manufacturing
Addon Name	Scenario
Trimergo	Project Management

Process Industry
Addon Name	Scenario
BatchMaster Enterprise	Manufacturing ERP

Cross Industry
Addon Name	Scenario
Altec doc-link 2.4	Document Management
CF Line	Cash flow and forecasting and treasury management
Crystal Wave	Document Delivery and Reporting
Clarity and Paymate 2.80	Payroll and Time Entry
Credit card application 7	Credit card processing
Easy ADC 2	Credit card processing
eBRIDGE Integration solution 2006	Integration
Enprise Job Costing V113X	Job Cost Managemnt
eXamin Fusion 1.1	Database Management, Data Migration
Fixed Asset Manager	Asset Management
iBOLT	Business Integration
Coresuite Framework	Technical Integration of add ons
B1 Usability Package	Usability