This website provides excellent practice exercises for interpreting both NMR and IR spectra. Many of my students express the desire for more practice problems in these areas and this website is certainly one that will provide many problems for both types of spectroscopy. Splittling the problems into differing levels of difficulty makes the problems far more approachable than if they were mixed together. Providing overviews of both types of spectroscopy and tables of familiar peaks makes the website all the more valuable.
The zoom feature is wonderful to see splitting in the H1-NMR spectra, though, as other commentators have noted, its usefulness in IR spectroscopy leaves a bit to be desired.