If you need to share a confidential file to one of your colleague and you have not enough time to manually encrypt the file before uploading it to a you may consider to use securesha.re.
This online service let you to share a file through its online service encrypting it before it is uploaded to the securesha.re servers.
DevStash.io uses a 128-bit client-side AES encryption through a SSL protocol. This website automatically offers a 40 charaters long, randomly generated password that can be changed by user if he/she prefers to use its own passphrase.
Moreover securesha.re keep the file reachable in a long, random URL to decrease that files could be discovered through a brute force search.
Last but not least, this website let you delete the uploaded file after a pre-defined amount of time or/and after a pre-defined number of views. The default configuration allows just one view and an automatic deleting after seven days but the views can be extended till 10 and the amount of days reduced to just 1 day.
Personally I normally prefer to encrypt files by myself before sharing them online but I will keep securesha.re in mind in the case I need to share a file and I have not my laptop with me.