I usually find it very difficult to simulate a real world scenarios whenever I want to develop or test applications that are targeted for mobile devices. I usually find it difficult to access the experience that my apps would bring to table for an end user. It was just few months back when I was introduced to WANEM by one of my colleagues.
WANem is a Wide Area Network Emulator, meant to provide a real experience of a Wide Area Network/Internet, during application development / testing over a LAN environment. Typically we application developers develop applications on a LAN while the intended purpose for the same could be, clients accessing the same over the WAN or even the Internet. WANem allows the application development team to setup a gateway which can be used to simulate WAN characteristics like Network delay, Packet loss, Packet corruption, Disconnections, etc and trust me there are a whole lot of network parameters that we can fiddle around with. But what is really cool about WANem is that it takes hardly 5 minutes to set it up and have is running.
Another gem of a (Open Source) tool.
You can get more information about WANem at http://wanem.sourceforge.net/