Paper Low-Enroute charts and Plate are available for download. I's actually a service porvided by the FAA. It is pretty cumbersome and extensive but for occasional use it might be handy for some. Having redundant backup, hard copy, etc is always the best practice.
Low Enroutes available at http://aeronav.faa.gov/index.asp?xml=aeronav/applications/IFR/chartlist_enroute
IFR Plates available at http://aeronav.faa.gov/index.asp?xml=aeronav/applications/d_tpp
These are only available for the cycle time and not earlier that 24 hours prior. I hope this helps.