Absolutely - I'd love it if some of the energy efficiency grants would also go towards shutters (which can work for cold in the winter too). Not so useful for rooms you're actually in, but great for keeping a room at home dark and cool whilst you're at work.

Blinds are probably a lot better than curtains at this time of year as well. Most people (myself included) tend to leave rooms with "whatever they already had in them", but it wouldn't be a great hardship to swap curtains out for blinds for some of the year.