João Luís

WordPress allows you to define a site logo (through Jetpack) and a site icon, why would you need to upload another image to use in your login page?
This plugin allows you to forget the login page. Just activate it and all the magic is done for you. No extra steps required.
The plugins uses the site logo if it exists, otherwise it will use the site icon. If none of them exist, the plugin will not touch your login page.

JL Login Logo

Uses your site logo (defined through Jetpack) or your site icon as the logo on the login form.

Jeremy Herve

Extends the Jetpack plugin and allows you to add sharing buttons anywhere inside your posts thanks to the [jpshare] shortcode
Important: for this plugin to work, you must activate <a href="https://wordpress.org/extend/plugins/jetpack/" rel="ugc">Jetpack</a> first, and activate the sharing module.
This plugin is a work in progress. You can report issues <a href="https://wordpress.org/support/plugin/jetpack-sharing-butttons-shortcode" rel="ugc">here</a>, or submit a pull request <a href="https://github.com/jeherve/jp-sd-shortcode" rel="nofollow ugc">on GitHub</a>.

Sharing buttons shortcode for Jetpack

Extends the Jetpack plugin and allows you to add sharing buttons anywhere inside your posts thanks to the [jpshare] shortcode

JL Login Logo vs Sharing buttons shortcode for Jetpack