I don't have any Irish ancestry, and haven't done any research in Irish resources. I was aware that the Boston (MA) Pilot newspaper had a column called "Missing Friends" for a long period of time, but I didn't know that the transcribed data was online. I saw the link while perusing the http://GlobalGenealogy.com web site.
Boston College has online transcriptions of the "Missing Friends" columns here. The database is summarized below:
From October 1831 through October 1921, the Boston Pilot newspaper printed a “Missing Friends” column with advertisements from people looking for “lost” friends and relatives who had emigrated from Ireland to the United States. This extraordinary collection of 31,711 records is available here as a searchable online database, which contains a text record for each ad that appeared in the Pilot.
The advertisements contain the ordinary but revealing details about the missing person’s life: the county and parish of their birth, when they left Ireland, the believed port of arrival in North America, their occupation, and a range of other personal information. Some records may have as many as 50 different data fields, while others may offer only a few details. The people who placed ads were often anxious family members in Ireland, or the wives, siblings, or parents of men who followed construction jobs on railroads or canals.
These “Missing Friends” advertisements provide a window on the world of Irish immigration. For further resources and more about the history Irish immigration, the Great Famine, and the Pilot, visit the History or Resources pages.
This database seems invaluable for researchers looking for their Irish ancestry.