List of up-converters to allow HF reception with RTLSDR receivers.

Blog about cryptography (in german).

Collection of software for reception of various satellite signals, ADS-B receiver (http://www.satsignal.eu/raspberry-pi/dump1090.html) for the Raspberry Pi, NTP (http://www.satsignal.eu/ntp/Raspberry-Pi-NTP.html) and more.

Hardware TRNG with USB interface, $25.

The Entropy Key is a small, unobtrusive and easily installed USB stick that generates high-quality random numbers, or entropy.
The Entropy Key contains two high-quality noise generators, and an ARM Cortex CPU that actively measures, checks and confirms all generated random numbers, before encrypting them and sending them to the server. It also actively detects attempts to corrupt or sway the device. It aims towards FIPS-140-2 Level 3 compliance with some elements of Level 4, including tamper-evidence, tamper-proofing, role-based authentication, and environmental attacks. If it detects that one of its two generators has failed, may be about to fail, or if it detects a physical attack, it will automatically shut down.
£36, but currently (Jan 2015) out of stock.

Small battery-backed real time clock for Raspberry π and Arduino.

Blog of the privacy activist Simon Davies.

Intel-based laptop and Tablets trying to use only free software (including BIOS etc.).

On-line tool to learn about cryptography. Supports a number of encryption methods (including Enigma).
An off-line version can be found on http://www.cryptool.org/

Ruby-based package manager for OS X.