We just crossed 80K 30 days active users. Our Alexa rank is hovering around 70K. We still have very few paid customers, though with the large number of visitors, we are able to make some decent revenue from ads.
The majority of our traffics (>90%) is from search (mostly Google). To get here, we did a lot of heavy SEO and page speed optimization. It took a long time to see results, though now we are seeing user growth at around 5% week over week.