Accommodation in St Ives
http://www.onestives.co.uk/ for pretty much everything you can know about St Ives.
http://www.stives-cornwall.co.uk/ The St Ives Hoteliers and Guesthouse site.
There are holiday companies where you can book self catering properties. http://www.stivesholidays.com/index.htm
Also Aspects, Cornish Riviera, Powells, Carbis Bay Holidays.
http://www.chycor.co.uk/ is a site a lot of locals use to advertise their properties with.
We have a Back packers http://www.backpackers.co.uk/st-ives/
A campsite in town which also has lovely caravans. http://www.ayrholidaypark.co.uk/
That is by no means an exhaustive list but will hopefully get you started.
Oh and if you want to know more about St Ives have a look at this film on You Tube. http://www.youtube.com/watch?v=4qIkJBTrJ_M I love the music which is played by Bagas Porthia a local group. Keep an eye out for their performances at various times throughout the year.