Upoading files

I want members to be able to upload a file other than an image - for example a 'pdf' or a 'doc'. And for the pdf link to be displayed instead of an image.

I want to use this in the 'create group' area. So, for example, instead of selecting a group profile image, I'd like members to be able to have a link to a word document or pdf file.

Anyone got any ideas???????