is there an easy way to upload a spreadsheet here or do I need to use something like dropbox and a link?
InvestorsHub cater for images, but nothing else as far as I am aware. I have some web space provided by my ISP that I sometimes use, in other cases I might use GoogleDocs as you can upload a spreadsheet and share that (such that others can download it in their own preferred format (xls, ods etc)). Or googledocs also cater for creating directories/files that can be shared. I think my free account version has something like a 15GB limit.