Cakewalk have been producing excellent quality music-related software for years. There are a number of products, but the one we have used is Music Creator. It's not mind-numbingly expensive and has all of the functionality we want.
This is far and away the best Tab editor we've seen. It's more than that though - it handles MIDI, ABC and ASCII files (both import and export), understands a wide variety of stringed instruments (you can even invent your own), and even has a free player. Enough of that, we're not on commission! Check for yourself. If you use (or want to use) guitar tab, download the demo and give it a try. If you want to listen to the examples on our site, you'll need the free player anyway.
Acoustica MP3 Audio Mixer
The sound samples on this site have been created and manipulated using MP3 Audio Mixer from Acoustica. It's one of those pieces of software that you can use 'straight from the box'. Acoustica's underlying philosophy is that 'Software Should Be Easy To Use' and they've certainly adhered to that with this. Its main benefit (for us) was its ability to save the sample in any of the major formats currently in use on the web.