Okay, here my personal list of islands where I have been in Europe. I hope I got them all:
Germany
EDWJ
EDWL
EDWG
EDXH
EDXW
EDXY
EDCG
Denmark
EKAE
EKVO
EKFM
EKEL
EKSS
EKAT
EKLS
EKRN
Norway
ENAL
ENSH
ENKB
ENHF
Sweden
ESSV
Finland
EFMA
Netherlands
EHTX
Italy
LIPV
LIRJ
Sicilia (LICP/Avola)
Sardenga (LIEA, LIEE, CAstiadas)
Malta
LMML
Croatia
LDSb
LDSH
LDLO
Greece
LGMK
France
Corse (LFKO, LFKJ, LFKC, LFKT)
LFDP
LFEA
LFEQ
LFEC
Spain
LESB
UK
EGJB
EGJJ
EGHJ
EGHE
EGEI
Ireland
EIIM
Looking on the long list it seems, that I could be named an island hopper. 
In my opinion planes are made for islands. It‘s most of the time the fastest way to reach an island. And regarding wind, often it is a challenge too.
That’s a really impressive list! Very few people will be able to get anywhere near it. I have done a lot more Greek island than you but that was in the “good old days” when it was cheap and easy.
La Gomera Island in th Canary Islands is a great place to land : like an aicraft carrier 700 feet high. Also worth to visit and far away from « main roads ».
Flores, Azores.
I have to update my list. After visiting Visby again, we flew to Kuressaare (EEKE). An island worth the trip and it might be a good location for a fly-in in the north: instrument approach, asphalt, enough parking space on concrete, Avgas, nice hotels and restaurants in walking distance to the field, a beach near the town, customs and at the time really good weather. So @peter it fulfills all off the points.
Then we continued to Kumlinge (EFKG) with its red runway. Very nice.
So here the updated list:
Germany
EDWJ
EDWL
EDWG
EDXH
EDXW
EDXY
EDCG
Denmark
EKAE
EKVO
EKFM
EKEL
EKSS
EKAT
EKLS
EKRN
Norway
ENAL
ENSH
ENKB
ENHF
Sweden
ESSV
Finland
EFMA
EFKG (new)
Estonia
EEKE (new)
Netherlands
EHTX
Italy
LIPV
LIRJ
Sicilia (LICP/Avola)
Sardenga (LIEA, LIEE, CAstiadas)
Malta
LMML
Croatia
LDSb
LDSH
LDLO
Greece
LGMK
France
Corse (LFKO, LFKJ, LFKC, LFKT)
LFDP
LFEA
LFEQ
LFEC
Spain
LESB
UK
EGJB
EGJJ
EGHJ
EGHE
EGEI
Ireland
EIIM
That’s an amazing list Peter. Have you done a list of ones which you haven’t been to? There can’t be many, especially with decent runways. In Croatia there is Unije but I doubt it’s doable for you.
There are many islands I haven‘t been yet. In Estonia there are some more, in Sweden I do also know two islands missing on my list and in UK there are many, especially in Scottland. But to go there is normally blocked because we do have our dog with us. Otherwise you couldn’t stop me flying to all of them.
The Greece islands are also worth a trip, but you know Fraport … and Croatia, Krk island is missing too. And LDPN Unije seems to be closed. I couldn‘t find it with Jeppesen.
@LimaVictor: another Canary Island worth visiting is El Hierro. Great small island, great diving, seafood, etc.
My list of island airports:
UK:
Alderney EGJA
Guernsey EGJB
Jersey EGJJ
Bembridge EGHJ
Scilly Isles EGHE
Isle of Man EGNS
France:
Corsica / Calvi LFKC
Corsica / Bastia LFKB
Not sure if France has any islands which are not FR-only
Germany:
Heringsdorf EDAH
Peenemunde EDCP
(looking at the map the above are technically on an island )
Italy:
Sardinia / Caglieri LIEE
Elba LIRJ
Spain:
Menorca LEMH
Croatia:
Mali Losinj LDLO
Brac LDSB
Greece:
Corfu LGKR
Skiathos LGSK
Leros LGLE
Kalymnos LGKY
Ikaria LGIK
Crete / Hania LGSA
Crete / Sitia LGST
Santorini LGSR
Milos LGML
Lesbos LGMT
Kithira LGKC
Mykonos LGMK
Astypalea LGPL
Samos LGSM
Hope to add Karpathos LGKP and Kastelorizo LGKJ in September.
I think that’s it.
Here’s my island list:
Ireland
EIIM Inishmore
EIIR Inisheer
EIIN Inishmaan
Isle of Man
EGNS Ronaldsway
Scotland
EGPI Islay
Glenforsa
EGEY Colonsay
EGEL Coll
Isle of Skye
EGPL Benbecuala
EGPO Stornoway
France
LFEY Ile D’Yeu
LFEA Belle Ile
Germany
EDWR Borkum
EDWJ Jusist
EDWY Norderney
EDWG Wangerouge
EDWL Langeoog
Denmark
EKRK Roskilde
Channel Islands
EGJA Alderney
EGJB Guernsey
EGJJ Jersey
It would be very hard to pick which my favourite is though!
