Between this and HNSearch, maybe your programs don't have to hit HN itself too much.
All articles start: GET http://api.hnstream.com/news/items/
All articles next: GET http://api.hnstream.com/news/items/?since=cursor:{last_cursor}
All articles stream: GET http://api.hnstream.com/news/stream/
All comments start: GET http://api.hnstream.com/comments/items/
All comments next: GET http://api.hnstream.com/comments/items/?since=cursor:{last_cursor}
All comments stream: GET http://api.hnstream.com/comments/stream/
Per-article comments start: GET http://api.hnstream.com/news/{article-id}/comments/items/
Per-article comments next: GET http://api.hnstream.com/news/{article-id}/comments/items/?since=cursor:{last_cursor}
Per-article comments stream: GET http://api.hnstream.com/news/{article-id}/comments/stream/
The "all comments" API is being used below, to display the latest comments as they are posted.