http://www.scdb.info/en/ is a great source of speed and red light camera points.
SCDB claims to have more than 100k of cameras in their database and having daily updates.
SCDB requests a 10EUR (appr. $13) payment for an annual access to up-to-date speed and red light cameras data. SCDB provides worldwide data, with ability to limit the download by country or multiple countries.
If you decide to use SCDB as your source of data, you'll have the minimal effort for importing them into speedometer. Just pick iGO (iGO8) download format, send the downloaded file to yourself via email and open with a speedometer using the "iGO" option.
Limitations.
For $13 (10EUR) SCDB don't provide cameras directionality and direction type. As they do own (I think) the Germany's "Blitzer" app, they probably just keep that away from regular users to have some competitive advantage. Though they do have speed limit of a cam and cam type (speed, speed/red light or pure red light) and that makes their data quite usable.
A note from the app author.
I'm using SCDB as one of the sources and will continue to use it, but I need to let you know that should you have support requests, they probably are not going to be answered as none of my requests have been. I was asking for how to get the camera direction and direction type to be downloaded and even went far enough to ask for a refund of my annual payment after having no answer. But this refund request have never been answered as well. So the site works and provides almost daily updated data, but don't expect anyone from SCDB to help you if you have a problem or a question. Strange way of doing business from SCDB, a good anti-pattern for us to experience and never follow :).
Links:
Remember speed limits
Complete showcase video and text manual.
Speed cams
Short video tutorials: Drive, Setup, Edit, Import/Export.
Text manuals:
‣ Edit waypoint/poi type, course, speed limit, direction type