I try to save most things on Pintrest, because it allows saving pictures with a direct link to the source.
You can search the Swedish museum archives by graves: Birka chamber graves or by a specific criteria: search on Historiska.se.
Sweden: Nordiska Museet
One way of searching for Norwegian finds is this site: Universitetsmuseum, or search for pictures with a keyword here: Fotoportalen, Unimus.no.
Academia.edu is a great source of articles.
Museums with digitalised archives:
Śląsk Opolski Muzeum
Victoria and Albert Museum
[this page will be constantly changed, as new sources will be added]