One of the cooler tools in the now free Professional Services Tools Library is the 1099 Modifier. The common scenario is that a vendor was not properly setup as a 1099 vendor and now there are transctions not marked as 1099 transactions.
The 1099 Modifier tool allows you to fix this by updating vendor 1099 amounts after setting the vendor 1099 flag.
You can also choose to just print a report showing what changes the 1099 Modifier will make when you run it.