RTL-SDR dongles and other SDRs are often used on single board computers. These small credit sized computers are powerful enough to run multiple dongles, and run various decoding programs. Currently, the most popular of these small computers is the Raspberry Pi 3.
Just recently the Raspberry Pi 3 B+ was released at the usual US$35 price. It is an iterative upgrade over the now older Raspberry Pi 3 B. The 3B+ has an improved thermal design for the CPU, which allows the frequency to be boosted by 200 MHz. WiFi and Ethernet connectivity has also been improved, both sporting up to 3x faster upload and download speeds.
The 3B+ also implements new Ethernet headers which allows for a cleaner Power over Ethernet (PoE) implementation via a hat. Previous PoE hats required that you connect the Ethernet ports together, whereas the new design does not. PoE allows you to power the Raspberry Pi over an Ethernet cable. The official PoE hat is not released yet, but they expect it to be out soon.
The faster processing speed should allow more processing intensive graphical apps like GQRX to run smoother, whilst the improved WiFi connectivity speeds should improve performance with bandwidth hungry applications like running a remote rtl_tcp server. PoE is also a welcome improvement as it allows you to easily power a remote Raspberry Pi + RTL-SDR combination that is placed in a difficult to access area, such as in an attic close to an antenna. Placing the Pi and RTL-SDR near to the antenna eliminates the need for long runs of lossy coax cable. If the Pi runs rtl_tcp, SpyServer or a similar server, then the RTL-SDR can then be accessed by a networked connected PC anywhere in your house, or even remotely over the internet from anywhere in the world.