Avalara's Avatax product provides automated sales tax calculation and data collection/aggregation from GP for ease of maintaining sales tax configuration in GP, and also sales tax reporting at the various municipal levels (state, local, etc)
There are several auditing solutions in GP both built into GP and through ISVs like TitaniumGP and Rockton: Activity Tracking (available out of the box): Allows for tracking virtually any table within GP to track such things changes to master data...
Extender allows creating custom windows and fields as either standalone windows or tied to existing windows in GP
If customer would like to track data that does not have a location natively in GP can use Extender for this purpose avoiding customization. Two GP customer examples: Nachurs uses a window tied to the Sales Transaction Entry to track what SO's in U...