Here is a summary of some secure file sharing tips culled from Twitter thread over the weekend.

hushfile.it – Encrypts the file before uploading it for sharing. Recommend you encrypt it yourself first.

hushfile Github Repo – You can also host this on your own server.

keybase.io – Slack-style app which uses end-to-end encryption, which includes file sharing option.
Firefox Send – Send files using this Firefox Test Pilot project. Links last 24 hours, and are deleted after reception. Recommend you encrypt the file yourself before sending.
Tresorit – Dropbox-style file sharing/sync app that claims zero knowledge and end-to-end encryption.

No recommendations from me, just pulled the more popular options from the list. One thing I was not able to determine was the intent of the file sharing. If you need to securely share with a third party, then services like hushmail or Firefox Send would be your best options. There are also several cost-based options here like Citrix SendFile. On the other hand, if you are sharing files with a workgroup then Keybase and Tresorit are a better option. Even a self-hosted OwnCloud would be a solid option here, provided it was correctly configured.