As the title says.

I am not hoping anything but i will just try.

Bring Down the Sky - it's free

I haven't really looked for actual mods to the ME series. They didn't feel like they needed any to me.

In terms of DLC though, pretty much bring down the sky. I think it carries over to some small parts of ME2 and 3 ( i remember it being mentioned in 3 at least ).

This + High Res Texture Mod and you're set up :)

http://www.moddb.com/mods/mass-effect-1-new-texture-updatesimprovements-mod

Here's some good explanation on how to make it work:
http://social.bioware.com/forum/1/topic/128/index/8565134/1

Or this?:
http://social.bioware.com/forum/1/topic/128/index/5314761/1

I personally recommend not playing the sequels. They were so dumbed down it was kind of sad.

Yep, that would be a good alternative too.

I've found those texmod textures to be glitchy in ME1, at least the ones I used, and the bigger ones degrade performance too much.

Here's a tweak guide that may come in handy:
http://www.tweakguides.com/ME_1.html

Here's the wiki tweak page:
http://masseffect.wikia.com/wiki/PC_Tweaks

Note: There's a few issues with the audio in ME1. It uses Creative's proprietary ISACTAudio through OpenAL. If you're interested in getting help with this grinninglich, then first post your audio setup and operating system that you have. I can help you get the most out of the audio.

There is this one bug where menus glitch out from time to time, and that requires alt+tabbing to straighten the picture, but I didn't experience any other problems, and finished the whole game with the texture mod. But I agree that your experience may vary with those things. Unreal Engine 3 really sucks when it comes to any kind of modding.

Yeah, that's probably the same glitch that I recall. There was 1 or 2 large texture mods that I tried too that slowed initial game launch way down, and I can't remember how it affected the game performance once it was started.

That was enough for me to take a pass on texmod. For any real modding you would probably have to be familiar with the Unreal Engine editor and be willing to hack and alter the game files. Probably something that you would want to upload anonymously once you're finished, if you wanted to share. :P

Mass Effect 1 had only 2 DLCs - Bring down the sky and Pinnacle Station.
BdtS added a few quests (nothing extraordinary), which enabled 2 or 3 minor references in later games.
Pinnacle was basically arena matches over and over again, for those who wanted to cap their chars in the first play-through - only one reference in later games as far as I'm aware and this was also available for those who didn't bought this DLC.

Never felt the need getting texture packs for it, so I can't recommend anything in that department.

Yes, 2 and 3 had significant changes in gameplay with a lot of elements being dropped. Yes, one could consider later games cover based FPS with the dialog being the only remaining rpg element. Still, if you enjoy the first one, you'd probably want to get / play them anyway for story reason (even despite the ending).

Bring Down the Sky is the only DLC that has any real impact in the later games, it also introduces the Batarians visually for the first time from the game perspective Pinnacle Station is very repetitive and doesn't really add anything story wise.

Only other recommendation I would make is to do a search on fixing Garrus' facial textures. The PC version always loads low detail textures in ME1 but there is a manual edit/tweak you can make to fix it.

Avoid the sequels like a crotch rot. I love ME1, whereas ME2 is one of the ten worst games I have ever played, and the most disappointing by far.