The
Speech Accent Archive is a really interesting site. It has speakers from all over the world and of many different L1s reading a passage aloud in English. I believe this passage is designed to showcase as many different segmental characteristics in English as possible. You can hear different speech samples if you click on the "language/speakers" link or the "atlas/regions" link, and you can see what sounds many different languages contain if you click on "native phonetic inventory". There are two main things I find useful:
1) If your students are having trouble understanding certain native English-speaking dialects, you can go to
this page. You can hear a huge number of different accents.
2) If you as a teacher want to find out different problems students from different regions will have, you can click on the "language/speakers" link or the "atlas/regions" link and the site gives very specific issues students may have with English as well a sample of their speech.