Cult Pens is a very hand web site, not least because they give good advice.  I asked them a question last night and got an answer back this morning - which is impressive at what must be a very busy time of year for them.

I'll put their answer here, because I suspect other people have often wondered which fountain pens take which refills.

Notable brands that DON'T accept standard cartridges are: Parker, Sheaffer, Cross, Platinum and Lamy.
Major brands that DO use standard cartridges are Faber-Castell, rotring, Porsche, Caran d'Ache, Waterman, Tombow, OHTO, Platignum, Pelikan, Visconti and Schneider.

That reply means that I'll be buying a Tombow pen rather than a Parker.  I want the option to use different colour refills.

Cult pens is also the place where I finally found the 2B pencil leads I wanted for my beloved propelling pencil.  They have a fabulous range of stuff and all sorts of useful information.  If you want a pink rollerball with a rubber grip ( to invent something at random), the odds are good that they will have it and you'll be able to find it easily.