OK in the interest of keeping my sanity and to prevent this question from being asked over and over... and for those that simply cannot be bothered to use the search button! I will make this one a sticky.
There will never be a definitive list of stuff to look out for, so anyone reading this needs to bear that in mind.
On the ICTDI, the most common things to be aware of:
Cracked Manifold. If you smell fumes in the cabin or at the rear of the engine block, chances are it has a cracked manifold. It's covered by Honda for 7 years or 125k miles - no quibble.
Rattling Timing Chain - if your timing chain is noiser than normal, specifically pre-facelift cars (facelift have revised timing chain design) then you may be entitled to a new timing chain (+injectors as they need to be replaced too). Although this is also covered for 7 years/125k bear in mind this is a £4000+ warranty claim and Honda will most likely want to go through your service history to ensure it's been maintained properly.
Slipping Clutch. In 3rd or 4th gear, give the car a hard run on full throttle... if the revs rise quickly when the boost kicks in and then slip back down again, your clutch is slipping. There are various schools of thought on why this happens, and Honda themselves have issued technical service bulletins to their service teams to check the settings on the cruise control pedal switch to check for play (causing the effect of riding the clutch). I put it down to a few different reasons including a poor pressure plate design. Most of our members (myself included) who have had the slipping clutch, found that the friction plate was like new when removed but the pressure plate had adjusted to the last setting. You could keep driving for a year before it definitely needs changing but you risk damage to the flywheel. Bear in mind also that flywheel failure is rare, but not unheard of. If your Honda dealer says you need the flywheel replacing, then ask them to tell you what the freeplay readings are. Best news is that a new clutch fitted from Honda is £585 fixed.
Fuel Filter and general servicing. The ICTDI is a rewarding car to live with. BUT it MUST be serviced ON TIME and with GENUINE HONDA PARTS. Period.
If your car is suffering from hesitation, and sometimes a glow plug warning light then chances are your fuel filter needs replacing. It's the cause of 90% of issues we see on the ICTDI on this forum. Please replace it with a genuine Honda item and then continue further diagnostics if your problems persist. Sometimes the filter just needs bleeding..
The only other thing to bear in mind when servicing is Oil viscosity. The ICTDI needs to be run on 0w/30 fully synthetic oil. Do not listen to any other advice on this.
If you can afford it, try switching to Shell V Power Diesel - this engine does appreciate it.
Aside from this, things common to all Accords are issues with paint (very thin paint causing stone chip damage), some brake related problems on the rear of tourers due to collapsing brake hose... and from the top of my head.. that's really it.
Feel free to add to this thread with useful hints/tips that will add to the value of this thread.
Please refrain from banter to ensure this thread serves it purpose to newbies asking the same question!
Oh and free plug to me B) if you have an ICTDI, then you may wish to consider a remap from Elite Remaps (Stage 1 180bhp/295lbft with both power and economy benefits) Details below.