A thrill whenever something of mine shows up, a pang of regret when a new batch comes up and I didn't have anything ready, and disappointment when a new batch comes up but my queued item(s) weren't high enough in the queue to show up.
And then thrill as they get their first reads, first comments, etc.

Also... when I look at my history and see that someone read more than one story of mine (especially if they appear to have spent long enough on it to have actually read it -- one never knows though). And most of all when someone actually reads through a serial.
I am definitely an attention whore here... ah well, it's so much fun to have others appreciate one's efforts.