saving lines to a text file on the fly v.s. after finished - how to?

ok so i wrote a program to gather links from say 20 results pages from google & then i visit them in my webbrowser to check out keywords etc.
right now, i am using IO.File.WriteAllLines("file.txt", linkList.ToArray)
it writes them fine after it is finished downloading all the links from my parse function....
but sometimes i want to stop it early...& if i do, nothing gets written....so how can i write them on the fly, i.e. as each one is received?

thanks <3