This script takes a string of up to 8000 characters with a single character delimtier and returns a table with each substring in its own row. A identity column is also returned so you can easily find the n'th item in the list.
Script is similar to kmlakov's but doesn't require the item count and adds the ID in the result table.
To get all items:
SELECT * FROM master.dbo.f_reuParseList('aa,bb,cc,dd', ',')
To get the 3rd item:
SELECT * from master.dbo.f_reuParseList('aa,bb,cc,dd'), ',') where listid = 3