A fantastic collection of various deep space objects, imaged in HaLRGB by Jim Misti. Working with just the L (luminance) frames, before delving into HaLRGB combining, is great way to learn the ropes.
Results are free to publish, as long as they are credited "Image acquisition by Jim Misti".
StarTools does more than just help you make "pretty pictures".
As of 1.7, enhanced mouse controls are implemented; Zoom in.
StarTools' Detail-aware Wavelet Sharpening allows you to bring out faint structural detail in your images.
You can convert everything you see to a format you find convenient. Give it a try!