Giada is a minimal, hardcore audio tool for DJs and live performers. Just pick your sample, drop it in any channel, and start the show by using this tiny piece of software as a loop machine, drum machine, sequencer, live sampler, or effect (VST) host. Giada aims to be a compact and portable virtual device for production use and live sets.
MrsWatson is a commandline audio plugin host. It takes one or more plugins, sends an audio signal to them for processing, and saves the resulting output. Although the plugins think they are running in realtime, processing is actually done offline (this is not the same as the "offline" processing in VST terminology). This makes MrsWatson ideal for developing or debugging plugins, or processing audio on a server.