/r/serendipity is a meta-subreddit meant to broaden the perspective of its subscribers. It takes a popular entry from a random subreddit and posts it every few hours. If you want to increase your exposure to niche subreddits, or just your perspective on things on the web in general, serendipity might help you do that. But it might not. It's a bot, after all.
Serendipity requires a few packages, like
PRAW. You'll want to install the
requirements.pip dependencies into a virtualenv.
build_subreddits.py requires lxml as well, if you want to update
subreddits, which is not listed in requirements as it's a pain and
most people probably won't need it.
You'll likely want to stick these scripts in your cron, something to the effect of:
0 */3 * * * python /path/to/serendipity/main.py # Post a serendipity link every 3 hours
0 0 1 */3 * python /path/to/serendipity/scripts/build_subreddits.py # Rebuild subreddits list every 3 months