We have a host of options here. The packages we integrate with include (but are not necessarily limited to);
NetSuite, Xero, QuickBooks Online, MYOB AccountRight, MYOB Essentials, MYOB Exo, Dear Inventory, Attache, MoneyWorks, Reckon, JCurve, Accredo, Greentree, Ostendo, Metcash, Symbion, Sigma, Australia Post & even Google Analytics.
The above mentioned packages we typically have either a dedicated "plugin" for, or at least a very standardised interface option.
As an extension on this, we have many other options for more bespoke or custom integration needs, including;
Manual data import/export, automated data import/export, Submit Orders via a myriad of methods including direct database connections, file drops, FTP transfers, via email, via Webservices or using an API. In addition to this, Inzant has an API which would enable you to build a bespoke interface yourself if you wished.
Our "off the shelf" options combined with the more bespoke options available mean that we will always have a suitable solution for your needs.