dynlib is a collection of dynamic processing effects. They are built to be used in mx as insert effects.
r4mbc is a 4-band multi-band compressor. It uses 4th-order butterworth filters for separating the bands. Each band then uses a downward compressor as used in rcomp.
ragc is an automatic gain control meant to level the overall gain of a full mix. It reacts slowly in order to create the notion of a balanced gain while trying to be not noticable. It was originally developed for broadcasting audio streams to the web (see netpd-radio) in order to deal with tracks with vastly different gains, but it might be (ab-)used in netpd as well.
rcomp is a downward compressor. Its control chain is processed in audio rate. A meter and display can be enabled with the toggle.
rlimit is a basic, but fast limiter. It is able to look ahead in order to limit even very fast transients, which adds a latency of 88 samples (2ms @ 44.1 kHz). Lowering the threshold raises the gain accordingly (that’s how some brickwall limiters work). However, the maximum output amplitude can be set by the out ceiling slider and is never exceeded.