One of the last best-kept secrets of the Web 2.0 world is celebrating a milestone - its 30 millionth user - and may be headed toward an IPO, CNNMoney reports.

Photo-hosting service Photobucket is a Top 50 web property, according to comScore, welcoming over 15 million visitors a month and adding 80,000 new users a day. The company made money last year - most of it coming from advertising. It has also raised $14 million in venture financing.

The site hosts photos and graphics that users then link to blogs, newsgroups and other social-networking sites. It enjoys 70 percent penetration on MySpace, for example.

As Photobucket moves into the mainstream, its demographics are starting to tend toward the 35-40 age range. "A lot of them have kids. Scrapbooking is huge -Two Peas in a Bucket is seeing a lot of traffic," says CEO Alex Welch.