I am going to read for a master degree in development studies and am planning to apply for PhD programs for 2006 entry. Apart from the research proposal and the university qualifications, is there any thing I can do to 'boost my CV'?

I would try and get some experience in a lab environment, even if it's voluntary and over the summer. Any work expereince will stand you in good stead - you need to stand out from the crowd, a supervisor also wants someone who will fit in well with their current team. If you have good references and experience of working in a lab team it will go a long way.

Do you mean Third World Development or Developmental Biology?

I've just read your previous post, evidently you mean third world development, in which case I'd ignore the advice to get some work experience in a laboratory. Try one of the development agencies or charities - ask your tutors, they may have contacts and be able to help.