Box.net’s File Sharing app allows social network users to upload and share files of all kinds on their profile pages. It’s simple to set up a box.net account right from within the application, and once that’s done it’s easy to upload file and manage the folder structure you want.

I tested this within Ning, where it’s available within the current set of OpenSocial offerings. Depending on the kind of file you upload, you may also have the option to edit the file via the web; this service is provided through box.net by zoho.com. Unfortunately there was an error with this functionality while I was testing and I wasn’t able to edit the file. There’s also a preview function for many file types.

Via the app settings you can turn off downloading for mp3 files that you upload, and you can change the view and order of the file listings; the vertical height of the app updates on a page refresh to accommodate the number of files that you’ve added.

In general the box.net opensocial app is very well done, and it should be a terrific resource for network members to make files of all kinds available to their peers. Recommended.

Last.fm’s My Favorite Music app lets you display music that you like, and it lets you and other visitors to your profile page listen to snippets and some full length tracks in-page.

If you have aLast.fm account, you can also attach it to the application, and it will provide a list of you recently listened to tracks.

Generally speaking the experience is not quite as slick as you get from Last.fm’s Facebook app, but it features the same basic functionality.

Links in the OpenSocial app (this is also true of the Facebook app) take you back to Last.fm; having the ability to play music inline and explore another user’s musical taste is a nice addition to profile pages. I found a few non-specific errors using this app initially, but they have not been seen again in the last couple of days. Given that this is only the first iteration of the app, look forward to future enhancements and bug fixes.

Here are a couple of screenshots from a Facebook app called Scrabulous to illustrate my point:

Applications created via the OpenSocial APIs on the other hand can exist in many different social networks, and each of these may not be as open as Facebook with respect to advertising. So while it’s certainly correct to suggest that OpenSocial is a boon for Facebook developers because they can, without much effort, double or triple the number of potential users of their apps, there’s no guarantee that these users can be shown advertisements in the same way they can via Facebook.

I think an import addition to the OpenSocial API on it’s way to a version 1.0 is the ability for an application to know whether advertising is permitted as part of the generated application space. Until that happens, Facebook’s smaller user base may still be a more attractive prospect for some app developers.

They couched their data in terms of the ‘connections’ in their service rather than in raw numbers; while it seems like marketing spin, Alexa data correlates that they have indeed had a traffic surge due to OpenSocial, and they aren’t the only ones:

It will be interesting to see whether this initial traffic boost can be sustained.

OpenSocial allows developers to write a single backend for their application and then have it distributed widely, across various social networks, where it can adapt an appropriate look and feel and take advantage of the data provided by the network container. For social network users, OpenSocial means that a richer and more varied set of applications will soon be available for them to deploy on their profile pages.