We're glad you asked :)
There are 3-4 of ways of doing this.
1. Create a Tagged collection by selecting the Assets you want to share and tagging them with a specific Tag.
You can then search for the Tag in the portal and copy the resulting address bar URL and share any way you fancy.
The user will have to login to download but provided your account is publicly accessible they will be able to see the selection before hand.
Note: You can add (and remove) assets to the Tag, and therefore the same URL over time and security is preserved.
2. Select Assets into a basket and the click Save - to Save the Basket.
Name the basket and add a description or note.
Once you save you'll be presented with a URL that you can share.
Example saved basket
You can also recall the Saved Basket at any time from your user menu - under My Saved Baskets. You can view and add assets to the basket at any time, and therefore the same URL over time. Think of a Saved Basket as something akin to a Named Media Kit that you can share.
Note: You can delete a Saved Basket thereby preventing the URL from being useable, but you cannot delete Assets from a Saved Basket. If you need to remove Assets from a saved basket - you can just Add a baskets contents to your current basket, remove any Assets you wish to and Save to a new Saved Basket.
When you share a Saved Basket url, Asset security is preserved - so a user will have to be registered and have permission to download the Assets.
3. User either Send or Share buttons
You can use select Assets to a Basket and simply click the Send or Share buttons in the basket.
Send will share a link to Download the selected Assets - without login required.
Share will send a link to view the selected Assets - Login required to Download.
Happy Branding :)