For an obscure browser companion, Medium has certainly raised a huge round. The company — a social surfing tool that recommends web sites, much like Stumble Upon — has taken in $15m from a bunch of second-tier investors such as Commonwealth Capital Ventures. I suppose the venture must be a big deal in Colorado, its home state. Congratulations to Medium. But the execs, in their joy, got a little carried away, sending out to its list an email headlined, tackily, "Cha-ching!" (By the way, shouldn't that be "ka-ching"?) Startups do need to remember: getting funding isn't less like winning the lottery; and more like borrowing from the mafia. The more you take; the deeper the hole you've dug for yourself. So don't celebrate just yet.