I am a really big fan of in town check in,eventhough I travel HBO most of the time,I like to get a paper BP,discuss the flight load and possibility of seat blocking (where available) with the check in agent as soon as possible. Knowing what's the flight going to be like a day in advance really helps me.
I am just curious,are there many airports which offer the in town check in service?
I know these do:
HKG:Most airlines,appart from some LCCs. Available at 2 Airport Express Stations:Hong Kong and Kowloon. There is a requirement to purchase the AE ticket to access the check in hall.
KUL:Available for CX,MH,EK,EY,BI at KL Sental train station. There is a requirement to purchase the KLIA Ekspres ticket to access the check in hall.
AMM: RJ flights only at 7th Circle RJ office. Check in is open for all flights departing this and the next day. No requirement to pay for check in or buy any tickets,but checking in a piece of baggage will cost you around 2 or 3JOD (3-5USD),the fee is waived for OWE/OWS and J cl pax. Same goes for the bus from said office to the airport: 3JOD or waive your OWE/OWS card.
VIE:Austrian only?
UPD:
moondog
NNG (Nanning,China)

ffers in town check-in at the bus station in the MixC, but this isn't much more useful than online check-in if you have luggage.
txflyer77
ICN

ffers this but only (IIRC) for the home-town airlines, not foreign carriers.
televisor
ZRH/GVA:More in-country than in-town: ZRH and GVA offer check in the day before (same day in limited cases) at a bunch of railway stations in Switzerland (i.e. at most significant towns), but only on selected airlines. Similarly they offer transport back to your home station (any railway station). They even offer pickup/delivery from/to your own home, but that's more expensive.
US
MSPeconomist
In some huge USA convention hotels, you can check in and check your bag (for certain airlines) at a desk in the lobby for a fee. The Chicago Hyatt Regency had this service a couple years ago, although IIRC it was only available early morning through early afternoon and of course had an early deadline for bag drop relative to your flight's scheduled departure.
Germany:
MSPeconomist
Lufthansa Airport Express trains would do check in and tag bags on board for those with airline tickets for this (R.I.P.) special train service. At FRA, you left the bag on a big wheeled cart on the platform. IIRC there's still something like the bag drop for LH passengers, but no special almost nonstop (DUS-Koln-Bonn-FRA) trains with all comfy FC type seats and some at-seat F&B service.
Not operational/discontinued/status unknown:
moondog
PVG:Meanwhile, Shanghai has had a "City Airport Terminal" near jing'an Temple ever since PVG was opened, but I'm pretty sure it has never (as in not even for a single day of testing) been operational.
MSPeconomist
I haven't checked recently, but NRT used to do this from TCAT = Tokyo City Air Terminal for those taking the Friendly Airport LimoBus. At one time, the bus took passengers directly to aircraft and flights were held when the bus was late due to traffic, but it doesn't seem to be organized that way now.
LHR
MOW (SVO/DME/VKO)
BKK