dublinpilot
Your best bet will be homebriefing.com
tingtang
I've done a few hundred hours both VRF and IFR in the US and DUATS is basically a one-stop shop (i.e. includes weather/notams/routes/briefings etc) for flight planning both domestic and international, and it's all online.
We are a long way from that here in Europe and it will probably never happen. GA is just not big enough here, by one or two orders of magnitude, and the vast majority of private pilots don't go far enough to need it. Also Europe does not have a unified flying environment like the USA. VFR flights have to work they way around CAS, occassionally getting transits, whereas in the USA you can get C/D transits easily (generally). IFR flights need the Eurocontrol routings for which there is no publicly accessible and officially up to date autorouting tool. Weather is fragmented across Europe - the only unified services are tafs/metars and some basic charts like the sigwx.
But in practice there isn't a problem - you just need a collection of websites and then you can develop IFR routes, file VFR or IFR flight plans, get weather, get notams, etc.
On top of that we have PPR for many airports
and there is no way around that - you have to phone (in a foreign language) or fax (and wait for the reply).