I agree that the lack of libs is a real problem. My real world example: I have have a bunch of RSS feeds, and I want to regularly poll those feeds, extract some content, and add it to my site (pageonetimes.com).
Doing it with Arc alone is too much for me - for mysterious reasons get-http.arc isn't working for me. Even if it did, I would have to write my own rss parser. Instead I am using Ruby for this, and grabbing the RSS content, parsing it, and saving the results is about 10 lines of code using standard libraries.
What kind of problems exactly does get-http.arc give you? It's a translation of a piece of Common Lisp code I had written to be able to fetch RSS feeds. The CL version worked well for the task.
In my CL project I thought to parse it manually, but I've abandoned the project after finishing the HTTP part. I've never tried using it, but you could have a look at treeparse in Anarki, if you haven't done already.