Jem in Europe- Miscellaneous.  The following countries had Jem in some capacity or another, but I haven't got enough information on them to have their own pages :)  The Netherlands especially seemed to have a large lot of Jem items!
 
The NETHERLANDS
The Show: It was aired in The Netherlands.  The music was kept in English, the rest was dubbed. It is suspected that Jem was on for one time only and probably not the entire series.  Thanks to Allanieew for that info.
I have also been told that the entire show was kept in English and subtitled into Dutch, and was possibly only aired up to the Glitter 'N Gold episode.  Thanks to Martijn Tulp for that info.
Hasbro & other licensed toys:
All of the first year dolls, and probably the rest of the first year line (including the Rockin' Roadster, Backstager and Starstage) was available there, in Dutch packaging.  Here's a picture of a Dutch 1st Edition Kimber (Thanks Laura (Badgerprincess))
From the second year, I've confirmed Rock N' Gold Jem & Rio (most or all of which seem to be the Caucasian version), Rock N' Flash Jem, Rock & Roll (Curl to us) Jem, Clash, Raya, Video and Danse dolls sold in Dutch packaging. Martijn Tulp says Jetta and Synergy were not available there. 
It is likely the fashions available there were from the 6 language series (this seems to be the norm for Europe).  Martijn Tulp says that the following were NOT available there: 1987 On Stage, Flip Side, Smashin', Rio and Music Is Magic fashions.
Stickers (sheet, blue background)
Puzzle- boxed, MB, 200 pcs. Featuring Jem in Award Night in front of the Rockin' Roadster (night scene)
The easiest way to tell a Dutch box is by the Dutch text, for example, Pizzazz's box says, "Pizzazz, Van De Misfits".  It only says "Truly Outrageous" on it, there is no Dutch equivalent used.  The dolls appear to be very much the same as those available in the US. Dutch and French text mean the box is probably Belgian.  For more information on Dutch box differences, see Jem 1st year boxes
Jem Comic Books; Just like the UK and Italy, the comic books were released in Holland with a new cover, translated into Dutch.  Thanks to Pete B. for this info!
BELGIUM
The Show: I do not know if Jem aired there.
Hasbro's Toyline
Presumably, had most of the dolls available there, I have 2nd year dolls in Belgian packaging, I'm sure there must have been 1st year Belgian dolls as well.  It is likely the fashions available there were from the 6 language series (this seems to be the norm for Europe).  According to the catalogue, it appears as though the entire 1986 line was available to retailers.
Thanks to sven-ken of the Titi-chan forum, I am able to share scans of the 1986 Belgium catalogue!  Thanks also to Isabelle!
Other Jem Items:
I don't know of any yet, any information is welcome!