Electoral registers have featured in recent announcements from the UK’s two main genealogy websites. Findmypast.co.uk are working with the British Library to digitize historical registers whilst Ancestry.co.uk have teamed up with Peopletracer to provide a Living Relative search.
I haven’t been able to find a decent description of UK electoral registers online (if you know of one let me know), but they were established after the Reform Act of 1832 and listed those entitled to vote, initially very few people were listed but numbers grew after subsequent Acts of Parliament until they essentially became a list of almost every household in the UK.
After 2002 voters were able to opt-out of having their names in the edited version of the register (which is available to everyone) although they still remained in the full version (which is available to certain agencies). This means that after 2002 there are fewer people on the edited (public) register but it can still be a useful tool but it can still be a useful tool when it comes to tracing living relatives.
The announcement from Findmypast means that historical registers will become a lot more accessible, and I mean a lot more accessible. You really have to have a pretty good idea of where someone was living before you can find them, otherwise you have a mammoth task ahead of you. digitization and indexing will make these records a lot more accessible and useful.
The new Living Relative Search on Ancestry.co.uk enables members ten searches per day with a free preview of the basic results. Credits can be purchased to get access to more detailed results although from what I have seen the basic results are pretty detailed already. Information is drawn from edited electoral registers from 2003 to 2011, telephone directory records and land registry records. It should be added that this service is not unique, there are several other organisations offering similar services (including one available through Findmypast).

I have nominated this blog for One Lovely Blog Award
http://myfamilypuzzles.blogspot.com/2011/03/one-lovely-blog-award.html
Thanks Alison, that is really kind of you.
You have also reminded me that I have an Ancestor Approved Award that I haven’t properly acknowledged yet either.
There were definitely electoral registers around prior to the Reform Act of 1832 – prior to that it was just freeholders who could vote though. I’ve transcribed several for Wing. Search in your favourite online ebook repository (eg Internet Archive) to locate surviving earlier lists – they’re usually published as “Poll for the Knights of the Shire of the County of xxxx” or something else along those lines. I am looking forward to accessing post-1831 registers though, none of my ancestors were anywhere near freeholder rank!