Bryan Danforth's lab:

http://www.danforthlab.entomology.cornell.edu/

Atlas of Hymenoptera:

http://zoologie.umh.ac.be/hymenoptera/

Czech Hymenoptera:

http://hymenopteracz.sweb.cz/

Sphecid wasps:

http://researcharchive.calacademy.org/research/entomology/Entomology_Resources/Hymenoptera/

Christian Schmid-Egger site:

http://www.bembix.de/index.php/de/

Hymenoptera Information System:

http://hymis.de/fotos/topical/topical.php?nav1=topical

Czech research on aculeate Hymenoptera:

http://aculeata.wz.cz

Anthophila- an online repository of bee diversity, Victor Hugo Gonzalez Betancourt

http://apoidea.lifedesks.org/

Bees, Wasps & Ants Recording Society

http://www.bwars.com/