I've never just done a logo for a client. I refuse to just spend a day faffing about with it and then go 'here's an eps file and a jpeg, are we done?'. It doesn't give them a good basis for launching a brand and is quite unsatisfying from a design point of view.
I send out a brand questionnaire to anyone asking for branding which gives me a clearer idea of what they are after and whether other 'add ons' can be considered. I've got several branding packages ranging from fairly basic to comprehensive depending on clients needs. This could include things like formatted powerpoint presentation templates and word docs, business stationery, basic or comprehensive brand guidelines, defining house typefaces, colour palettes, email signature strips and possibly company literature, leaflets, e-newsletters etc.
Most people come to me asking for a logo and unless you drill down into their needs for their day to day business you are missing a bit opportunity to establish yourself as their (for want of a better description) 'brand guardian'.
If they see you as someone who does logos then you'll get a day or two's work but if they see you as an authority on their brand and understanding their needs they'll come back to you further down the line.
Of course their are always clients who will just see the price tag and walk away, but I'm happy with that as if they are not willing to spend on their core branding you would be unlikely to get much else from them long term.