The Nexus 7 comes with limited on-board storage, but you can use online storage service to increase capacity. With using any such service, it's easy to upload files, access the files, share with others, have backup and restory from any platform. There are cloud storage apps for Android offering best user experience on Nexus 7 tablet with WiFi network.
* Box for Android app offers free 50 GB online storage. It allows you to access, view, edit, manage and share files directly through a tablet, computer or mobile phone. One downside is the limit for video size, because no way to upload large HD videos.
* Dropbox is one of the simplest apps in Google PLay store. The free account gets 2 GB. Good enough for store documents and email attachments. It syncs data automatically and supports offline viewing.
* SugarSync offers 5 GB and comes with AutoSync Photo feature. It supprots multiple files uploading and music playback, but doesn't have search option.
* Ubuntu One Files/Music apps, used with single Ubuntu ID, give you 5 GB. YOu can upload images, videos, audio and other files. Avoiding uploading duplicate files is its crucial feature.