I was asked to increase the size of a column in a table from it's current value of 900 bytes to around 2000. Forgetting why I set the value to 900 originally, I found I was unable to create an index over 900 bytes (the table contains regular expressions for those wondering why I am attempting to index a column this big).

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/architec/8_ar_da_0ldf.asp

I can't find a workaround to enforce uniqueness on the table - not sure why this limit is in place. It doesn't appear to have changed for 2005

http://msdn.microsoft.com/SQL/2005/2005Webcasts/TSQLQandA.aspx

although there is a new feature called "included columns in indexes" which would solve problems in some cases but not in mine