If you need to quickly modify pdf documents on-line (e.g. before forwarding them), you cannot have access to your laptop and you don’t have the Administrator privileges on the computer you are using, you could be interested on the features offered by http://www.ilovepdf.com.
PRO: This website works without the need to install particular “interfaces” on your computer, it doesn’t seem to be invasive and the results, for my experience, are good. Moreover, it offers a real interesting bunch of features to “modify” and convert pdf documents.
CONS: It uses only HTTP protocol and, in any case, is an “unknown third party” so remember to not share any OFYE documents with them.