There are none that I know with 100% certainty, but there are a few types of businesses that are generally known to be fronts where I come from (and I suspect in many cities), and there are a few specific ones I'm confident are fronts.
Massage parlors are commonly fronts for prostitution all over the world, or offer "extra" services. This is so common that many of them have prominent signs explicitly saying they do NOT.
I swear, there must be more video stores than there are working VCRs in my city. And they seem to have kept mostly the same stock of VHS tapes for the past 30 years. They are rumored to be fronts for, again, prostitution.
I have strong suspicions about psychic readers. There are a ton of them, and many are open at odd hours of the night in places that are not busy enough to get any legitimate foot traffic.
Gyms are all fronts for...gyms. I mean, the gym business is corrupt enough that I feel like that counts.
If you are in NYC, usually, from my understanding they are fronta for multi-family kinda squat houses. That’s why the curtains are so close to the front door and you almost never see anyone in there…actually, in all my time I’ve never seen anyone in one of those places. But they’re all set up the same. Pull back those curtains and it’s like a huge illegal house
Helsinki is, for some reason, full of massage parlours.
There's a neighbourhood called Kallio that was formerly rather cheap but has become much more expensive and gentrified, and the massage parlours remain. I have no idea how they can afford their rent, as I've never seen anyone going into or coming out of one of those venues.
Obviously they provide "extra services", but I don't think that can be enough to sustain them. I suspect money laundering from drug sales etc.