2nd Millennium Invisible Calculator 

2nd Millennium Invisible Calculator allows you to make calculations in any place where it is possible to enter expressions (e.g. text editor, lines of input, etc.).
invisible calculator calculate in any place

Digital Ear Real-Time 

Digital Ear Real-Time can analyze a recorded or live solo performance (wav file) (e.g. a singing human voice, or a musical instrument) and convert it to a standard MIDI file. * NEW: Now in Real-Time! *
audio wav wav to midi midi converter wav2midi wave to midi audio to midi sequencer synthesizer

Xselerator 

It's got everything an XSLT Editor should have plus a bit more like Intellisense and tag auto-complete! It's also half the price of XMLSpy... so it's great value. A 30 day free trial is available.
xml xsl editor debugger xpath developer tool