ZXDS is an emulator of Sinclair ZX Spectrum for Nintendo DS, written by Patrik Rak. It accurately emulates Spectrum 48k, 128k and Pentagon, and supports SNA/Z80/SZX snapshots, TAP/TZX/PZX tape files, TRD/SCL disk files and RZX replay files. It has some other noteworthy features, like the ability to download all these files online over WiFi, the peer-to-peer WiFi multiplayer, or Kempston mouse emulation.