The NSF Center for Nanoscale Chemical-Electrical-Mechanical Manufacturing Systems has produced many interesting advances during its existence. It is well worth visiting the web site.
Superionic solid state stamping (or S4) is one such advance. S4 electrochemically transfers a pattern written in a superionic solid state conductor into a compatible substrate. For published details on the S4 process, refer to JVST B 25(6) Nov/Dec 2007, 2419-24 or Nano Lett., 2007, 7, 446-51 . For a pictorial overview, see the link at the bottom of the project page.
The Center recently combined S4 with metal-assisted chemical etching [Appl. Phys. Lett. 77, 2572 (2000)] to create silicon nanowire arrays as a demonstration project. At least for silicon substrates, the technique is reported [Nano Lett. 2010, 10, 1582-1588] to be capable of lateral resolutions approaching 10 nm along with extremely high aspect ratio. (The latter will likely be limited by mechanical integrity of the free-standing features.)
Along with S4, five other printing-related processes are under development at Nano-CEMMS. I encourage you to take a look at the site.