Peter - when are you going to be visiting? If it's before the end of May, the Brighton Festival and Fringe Festival will be on, so there's lots to do and see. Take a look at the websites:
http://www.brightonfestival.orghttp://www.brightonfestivalfringe.org.ukYou could call it the Anish Kapoor festival this year, as he seems to have a monopoly on pretty much everything that's going on. I would recommend a walk to the Chattri - a memorial to Sikh and Hindu soldiers who died in Brighton during the First World War - where one of the Kapoor sculptures is on show.
http://www.black-history.org.uk/chattri.aspIt's an interesting place to go even without the added interest of the sculpture, and a very pleasant 20-minute walk across some fields to get there.
The artists' open houses are some of the best things about the festival - not for the quality of the art, which is often pretty naff, but for the opportunity of poking around some truly gorgeous houses and gardens!
I agree with sausage100uk - if street photography's your thing, then the North Laine is probably your best bet. If you want more seascapey stuff, head east on the Undercliff Pass, past the Marina, towards Ovingdean where there are lovely rockpools at low tide (and a very nice cafe on the prom!). For a bit of industrial scenery, go west to Shoreham Harbour. For views across Brighton, go north on the Ditchling Road, park at Hollingbury Golf Course and walk up onto the hill fort,
http://matt.pope.users.btopenworld.com/hollin/Hollinhome.htm. On a good day you can see as far as the Isle of Wight.
Hope that helps! Have fun.