Hi
I have the same issue with .rtf files with my 16 Gb phone. did u resolve your issue? I tried a apps that claimed all sorts but it didnt work (nothing new there then!)
I believe the issue we are both having is trying to open a hyperlink written inside of a .rtf file.
My clients send me documents using the "insert as hyperlink" in rich text format e-mails. These automatically generate a hyperlink.
The iphone will not open this type of document. iFile will open the hyperlinked document once it is placed within the file structure of the phone. If this type of file is sent via an attachment to the email, then the combo of AttachmentSaver and iFile work great.
If the hyperlinked file is placed within the body of the email, then you need to either use iphonebrowser or SSH to copy and paste the file.