Tangible Instruments' new Arpeggio - a dedicated sequencer/arpeggiator that contains a 2-oscillator virtual analogue synth - has an almost toy-like appearance, but it also looks rather inviting.
Designed for composing, saving and performing melodies, it enables you to create and store sequences as you play, and offers a range of arpeggiator modes. You can chain together up to 512 user-created arpeggio patterns, and adjust note lengths and add rests to your sequence.
As as well as USB connectivity and audio outs, you also get MIDI I/O and CV/gate out, so you're able to sync the device with analogue gear. In fact, you can use Arpeggio to control pretty much any hardware/software synth you like, though the inclusion of an internal speaker and a battery powering option reinforces the impression that this is also an instrument to be taken anywhere and used standalone.
You can find out more and register your interest on the Tangible Instruments website. The price and release date are still to be confirmed.