Sting manipulation? Complex mathematical calcs? Heh... Let's have a race... let's start with string manipulation... How about splitting a comma seperated column and returning a table with the PK of each row and the split value... 1 row for every split on a 100k row table? You write a CLR to solve, I'll write the T-SQL to solve. I'll even be happy to provide the test data if you want.
Or, how about doing Init Caps on a column in a million row table?
Or, how about removing all characters except digits and letters from a column in a million row table?
Or, name the problem...
...and here's your advantage... I don't have 2k5 to play with... I have to do it using only T-SQL 'cause I only have 2k. 😉