A good example is Cisco WAAS, a cool video showing how it works is here: http://www.cisco.com/cdc_content_elements/flash/ans/index.html
See here for data sheets and specs: http://www.cisco.com/en/US/products/ps5680/Products_Sub_Category_Home.html
Cisco's solution is inexpensive and you can use your existing router investment to do all the heavy lifting.
"Don't worry about people stealing your ideas. If your ideas are any good, you'll have to ram them down people's throats." -- Howard Aiken