One of the great things about the community of people that have an interest in European railways is that there is always a heavy emphasis on sharing information in order to ensure that as many people as possible can get the maximum out of their hobby. Indeed, that’s the spirit in which this website was set up.
Central to this are a number of internet “gen groups” – generally Yahoo Groups. I would encourage you to join as many as you feel relevant to your interests, but most importantly, do please post to them as well as read others’ postings! Different groups have different guidelines as to what is acceptable material, but in general, the more information posted the better for everyone, and your “boring everyday sighting” may be the very piece of information that somebody is looking for. Most groups also include extensive collections of files including locomotive diagrams.
The “Daddy” of them all – in terms of it being the longest-established, the one with the largest number of members and the one that covers the largest area – is European Rail Gen. This covers information – predominantly haulage-based; both reports on trips in the recent past and advance notification of forthcoming workings – for all continental European countries, but not questions. Any questions are encouraged to be posted to its sister group, European Rail Discussion, which was set up for that very purpose.
There are a multitude of other country-specific groups – for example DB Loco Info (for Germany), Hunrail (for Hungary), CFR Rail Gen (for Romania), Polrailgen (Poland), SNCF Rail Gen (France) and Belgen (for the Benelux countries) – please do let me know if you are aware of others.
There are a number of other sources of gen which work a little differently but are invaluable, especially on the ground.
My favourite – and something that I wish was adopted universally! – is the MÁV “mapper” (http://iemig.mav-trakcio.hu). This is essentially a rail equivalent of “FlightRadar24”, in that it gives you a Google Maps-based real-time GPS overview of the Hungarian rail network with moving dots symbolising trains moving around the network. Clicking on them gives you the UIC number of the loco or unit concerned, and also a stopping pattern if it is a passenger service. Combine this with the fact that most Hungarian InterCity services (and some others) have WiFi, and you can see how this can be an awesome bashing tool!
A similar system is NS’s “Treinenradar” (http://treinenradar.nl), covering the Netherlands. This can be narrowed down by traction type and searched by loco number, which is a massive bonus. Again, clicking on one of the “trains” reveals motive power details.
For most of the rest of Europe, on the other hand, it’s old school…!