Cross-Species Gene Finder (Java)
The first free, cross-platform tool to search for similar genes between two species using the NCBI database. Includes a batch mode.
NOTE: As of April 2017, this program does not work at all due to significant changes in NCBI's backend server. It will eventually be fixed, but I have no ETA.
ProxyDNS (C - Linux/UNIX/OS X/Cygwin)
Bypass DNS-based internet censorship when port 53, or even DNS packets themselves, are blocked by a firewall.
The download is a prebuilt OS image for the Raspberry Pi 1, 2, 3, and Odroid-W.