WaveShop - free and open-source audio editor, offering bit-perfect accuracy for unchanged samples. Features include cut/paste, peak and RMS analysis, normalization, fading, audio generation, and more.

It's essential to note that if you're using 64-bit Windows, you're strongly encouraged to upgrade to the 64-bit version of WaveShop. The primary reason being, it can load more and more complex files at once without running out of memory. Waveshop's list of features is expansive and includes the likes of clipboard (Copy/Cut/Paste/Insert/Delete), unlimited undo, normalize and/or fix DC offset, amplify (boost/attenuate), fade in/out/custom, linear or logarithmic, peak statistics, RMS statistics with histogram, reversal and inversion, find clipping with detailed report, extract channels to mono files, insert/delete/swap channels, change audio format, sample rate conversion, generate audio w/ envelopes and modulation, edit surround speaker assignments, find zero crossing, multiple document interface (MDI), multithreaded processing, playback via DirectSound, peak-hold meters with surround support, real-time spectrum analyzer, recording with no limit but disk space.
In summary, WaveShop provides a robust and intuitive environment for audio editing. Its simple and easy-to-use interface means that even beginner-level editors can familiarize themselves with the software quickly. If you're looking for a feature-rich audio editing software, WaveShop should be your go-to choice.
Version 1.0.13.000: more modern look (Common Controls 6.0); metadata editing; EQ, compression, effects via LADSPA plugins; channel selection, one-touch and sound-activated recording, sweep generation, AAC/MP4 decoding, MP3 encoding, static and real-time spectrum analyzers