Ok, Facebook. But what’s the next hottest company?

A year ago, we asked readers which company they thought was the hottest, i.e, offering the biggest chance of making them a millionaire, either through a pending sale or an IPO. Key question for job-seekers. Two companies that came to mind were Facebook, and YouTube – but in comments, readers listed almost every company of note.

If you’d have gotten into Facebook or YouTube around the time of that post, you’d be very fortunate right now. YouTube snagged at a huge $1.6 billion acquisition offer from Google, despite doubts about its business model. And one commenter at the time said Facebook, reported to have just been valued at the nine-digit level in a venture round, was too late to join. But that’s not true. It’s now clearly worth more than $1 billion, so we’re up to ten digits, and we’re only 11 months on.

So this year, Facebook still reigns supreme as the private company du jour.

You could argue it is now too late to join Facebook. But our opinion is, it’s still hot. But who comes in second? Tough question, and this year we can’t decide. Digg and Photobucket each got a singular mention last year. They’ve since both become very popular, and are both being bandied about as worth far more than $100 million. Do they strike you as fundamentally significant companies? There’s Glam Media, with a reported value of $150 million, but does the media company, boasting an albeit innovative business model, have legs and imagination to get really big? (See our coverage here: Digg, Photobucket (scroll down) and Glam).

A string of other companies are going public, or have filed to go public garnering high values. Aruba is just the latest, with an IPO giving it a market cap of $1 billion, for example, and there are others of this ilk — but do these communications and infrastructure companies have what it takes to become breakout companies?

What do you think? What’s are the hottest two private companies?

And please don’t say Justin.TV (coverage here) or Twitter (see coverage, lighter, and more serious) — at least, not yet! And which ones are we missing?

We’ll follow up in a few days when we think there’s a verdict.