Computers are great at identifying records that are exactly the same, but what about when there are records with different punctuation? (Start by agreeing on Alphabetizing and Data Entry Rules for your organization.)
I have already written flexible programs for data cleanup (for example using "San Francisco" consistently, when it was entered as SF, S.F., San Fran, and San Fransisco (mis-spelled); or having " St." consistently when it was entered as Street, St, and Str. I've imported data into Raiser's Edge from Excel, Access, Lotus Notes, dBASE, and other programs. I've merged data from different sources, doing data cleanup when addresses were entered following different conventions.
I can also automate importing data from web sites, so you don't have to re-type and proofread data; and you don't have to copy and paste each field one at a time. Importing saves a lot of data cleanup compared to retyping!
I have excellent success in identifying probable duplicate records. The reduction in costs from eliminating multiple mailings to the same household can be substantial. Of course most database programs come with a way of removing duplicate records, but need data cleanup first or the similar records get missed.
I also advise you what data is not worth cleaning up, and what records should be kept impeccably maintained. Before I clean up the data, I find out from you what fields you use regularly, what fields you don't use, and also how your having the data clean affects your organization and your communication with your donors.
I won't waste your money on data cleanup that doesn't affect your communication with donors! (Most technical people don't look at what's important to communication and what impacts donations, and so can't prioritize). If I can easily automate changes, of course I will, but I won't waste my time or yours on manually checking data that isn't important.
If you have data to clean up or import, Contact Me and we can look at how I can work with you to have your data be more useful.