Convert documents to PDF through the internet

Now, most means of converting a document (Word / Powerpoint, etc) are through a utility installed on the system. This utility will mostly rest as a printer, so that when the user wants to convert a document to a PDF, he/she will print to PDF. But there are other ways of doing this as well. One way is to utilize a service that will allow you to upload a document, ask you for an email ID, and then will actually send you the PDF to that email ID for free. And this is done for a fair number of different formats as well.
One site that does this is called PDFOnline, and is available at this link
These are the formats that can be converted to PDF through this service.

-MS Word (DOC)
-MS Publisher (PUB)
-MS Word (RTF)
-MS Excel (XLS)
-MS PowerPoint (PPT)
-MS PowerPoint (PPS)
-JPG, PNG, BMP, TIFF, GIF, WMF, EMF
-HTML (MHT)
-Text (TXT)