You get 34 most recent posts in all forums and topics on: feed.php
34 most recent topics in all forums with first post: feed.php?mode=topics
There are feeds to new posts in every forum category, such as:
per-forum feeds = Feed with 34 most recent posts from all topics in the selected forum.
URL = feed.php?f=[ForumID]
For example: feed.php?f=47
for the 34 most recent posts in Archos 5 Internet Tablet with Android forum section
Per-topic feeds = Feed with 34 most recent posts from the selected topic.
URL = feed.php?f=[ForumID]&t=[TopicID]
Enable active topics feed = Feed that shows Y last posts, not older then 7 days, for forums that have "Display active topics" enabled.
URL = feed.php?mode=topics_active
I dunno if I increase items to 100 or something if that may take too much bandwidth.