Peter. There are a few internet sites which have good identification advice and some include full identification keys but, regretfully, most just show photos without any information. And in many instances there are a number of superficially similar species which require examination of specific points for a firm identification.
I participate in this site which covers most aspects of UK wildlife, and will also include many Northern European countries.
http://www.wildaboutbritain.co.uk/forums/index.php
Plus, I have a bookcase full of information about various insect families including books (each with several hundred pages) and downloaded literature. I always prefer to print off as much as possible instead of trying to read it on screen.
But I still often have to ask for help with the more unusual or complicated cases. Such as your latest photo which is definitely a specialist subject.
The wing veins suggest Muscidae overall family and it has a hint of being a Pollenia species. But these are all complicated species which is currently beyond the scope of my knowledge; which is where I would ask for specialist help.
ps. Steve's spider is an easy one, Araneus diadematus (Garden Spider) female.