As in my experience the SKSE plugins (in Oblivion they were called OBSE plugins ) come without esp/esm and are easy to use and manage, I always use the harmless ones with pleasure.

So, I wanted to make a comprehensive list of these useful pearls of modding wisdom which improve the game.
So far, I know of these:

http://www.skyrimnexus.com/downloads/file.php?id=1175 which gives your character to gain levels and skills above 100. Elys claims the sky is the limit

http://www.skyrimnexus.com/downloads/file.php?id=1227. The plugin forces Skyrim to enable categories for containers (chests, wardrobes, etc).

Smart Soulgems (will insert link when I find it)

Please feel free to throw a link to any such plugin so we all could enjoy better game, after all, this is exactly why we play the PC version, right?

http://www.skyrimnexus.com/downloads/file.php?id=2006 - Skyrim Elys MemInfo
http://www.gamesas.com/topic/1300172-rel-smart-souls/ - Smart Souls

Okay why no one has mentioned this one is beyond me.

http://www.skyrimnexus.com/downloads/file.php?id=3863

Is there a sample for skyrim plugin around, the only sample I've seen is the old OBSE one.

The reason it wasn't mentioned is because it isn't an SKSE plug-in.

The OP meant mods that go in the SKSE\Plugins\ folder

Wrong, it requires SKSE and has this file

C:\Program Files (x86)\Steam\SteamApps\common\skyrim\Data\SKSE\Plugins\gibbed_interface_extensions.dll

as such it is a SKSE plugin.

Oh... lol My B

here's another:

Perk Points -- http://www.skyrimnexus.com/downloads/file.php?id=1367
it allows you to set how many perk points you're awarded when you level up with an .ini file inside the Plugins folder.

One has been included with the source code since the first release.

Elys Uncapper also allows you to set how many perks per level up.

TESV Acceleration Layer: http://www.gamesas.com/topic/1321575-rel-tesv-acceleration-layer/
gibbed interface extensions: shipping with http://www.skyrimnexus.com/downloads/file.php?id=3863