Olive Tree Genealogy has been putting actual images of passenger lists online for several months now. So far there are images of the passenger lists of ships to New York, New Orleans Lousiana and Baltimore Maryland.
These are graphics of the actual passenger lists - some are also transcribed, but some are not. The quality of the images varies from crystal clear to very faded, but that's always the fun of research. Reading someone else's transcript or index of a passenger list is okay, but seeing the original list for yourself is always best.
What a great opportunity to find out who else was travelling with great great grandma! I found my own great great grandmother's mother (and g-g-grandma's maiden name) on an image - her mother was travelling with her in 1831 as she made her way to New York City. I wouldn't have known she was her mother without seeing the original image.
Often there are comments about illness, deaths, stowaways, or other remarks. Occupations, places of birth and ages are often given. All these images and lists are free to researchers, as are all databases on Olive Tree Genealogy.
The index to images of ships passenger lists (the actual manifests) is at http://www.rootsweb.com/~ote/ships/