This is something close to my heart at the moment as I am designing a new identity for an organisation I volunteer with. Of course the logo and brand attributes are not the difficult thing, the really interesting part of the project is how we design to promote the charity and make the creative and content engaging for our older members, potential volunteers and for raising much needed funds.
I found the following Q&A piece with 'UX Matters' of great interest, I hope you like it too.
A whole host of leading design experts have contributed to the editorial. Please have a read Designing for Senior Citizens.