If you're away from your home computer and need to open a file on a foreign computer that doesn't have the program installed, there are a few options. For one, Gmail converts several file types so they can be viewed right in the browser, including PDF, PowerPoint, and Microsoft Office documents. However, it's not nearly as helpful for music files, as its only able to make a few listenable. Enter Koolwire, a simple no-frills service that converts several popular file formats under 10MB through e-mail.
Besides taking any Word, PowerPoint, or Excel document and turning it into a PDF, it'll also convert any PDF file to a Word document. Likewise, WAV files will be converted to MP3s and visa versa.
Here are the addresses for the different conversions. Add them to an e-mail address book to keep them handy, or create a group in Gmail (kind of counterintuitive since Gmail converts some files):
From word, ppt, excel to PDF: email@example.com
From PDF to Word: firstname.lastname@example.org
From WAV to MP3: email@example.com
From MP3 to WAV: firstname.lastname@example.org
The process takes a few minutes to convert the e-mailed files. Recipients will get the file attached to an e-mail message, along with some sponsored links in the message body that keeps the service afloat.
While Koolwire is handy, a far more powerful solution is Zamzar. It will take nearly every file thrown at it (up to 100MB), and churn it out into nearly 70 different formats for pictures, music, video, and Office files.