I need a photo collage app without lines in between pictures?

I'm looking for an app for a iPhone that can join my pictures with out a line or a Really thin one.

There are lots of photo collage software apps out there. Only you will know which ones do what you want.

Many apps offer a 14-day to 30-day trial download. You should start with one like this:
http://www.softpedia.com/...aker.shtml
And then try another one, until you find one that you like and can afford.

I would not count on finding a free application to do this, though.