Access is probably the most flexible and productive database front end on the planet. Use Access with SQL Server over your LAN, or with Terminal Services for remote users and you have an efficient and affordable solution. This is particularly true when your starting point is a mature application framework like the one AccessTools has developed.
In addition, Access 2010 has new capabilities which step outside the traditional client server pattern. Access Services applications work in conjuction with Sharepoint 2010 to provide both browser based and hybrid applications. Deployed as a hybrid application, Access 2010 runs locally as a desktop application which exchanges data with a remote server. Access 2010 hybrid application have support for disconnected clients baked in, so one can sync changes back to the server after working off of the network.
Microsoft SQL Server, PostgreSQL, Oracle
A relational database management system (RDMS) is used to store data and keep it safe. In general, an RDMS is more durable and secure than the native data store which Access provides.
Terminal Services/Remote Desktop
Terminal Services is a server technology that allows desktop or client server applications to be shared with remote computers via Remote Desktop. It's a great way to get an application distributed worldwide in short order.