Day of Defeat : Source is by far the best HL2 mod. My opinion. Even with Half Life Game of the Year Edition (circa 98), back in 01, when Day of Defeat was first released. Here are the Day of Defeat beta Mods, and of course, DoD:Source is now available.

    * Beta 1.0 (12 January 2001)
    * Beta 1.1 (14 February 2001)
    * Beta 1.2 (5 April 2001 ?)
    * Beta 1.3 (1 July 2001)
    * Beta 2.0 (13 October 2001 ?)
    * Beta 2.1 (10 May 2002)
    * Beta 2.2 (2 September 2002 ?)
    * Beta 2.3 (?)
    * Beta 3.0 (?)
    * Beta 3.1 (?)
    * Version 1.0 (1 May 2003) (retail)
    * Version 1.1 (14 November 2003, the first release on Steam)
    * Version 1.2 (19 May 2004)
    * Version 1.3 (7 July 2004)
    * DoD:Source - not released yet

I was very very lucky to be gaming when this mod came out, and still gaming today.

Here are some pointers, from which I have learned from experience.

RUN! the shift key is your friend, find the right times to use it.
STRAFE, always use your A and D keys, strafing is way to important!
RUNNING AND STRAFING, always do this, moving side to side quickly while using your pistol, can render you bullet proof!
going prone, this used to be fun when u could still fire your gun while going prone, made an interesting "prone/jump" attack, however, that glitch has been taken out. Prone (z by default) will keep u on the ground with sharpshooter skills.
croutching isn't so important with alot of the weapons, the ones that are single shot or require accuracy.. that's about it.

PRIMING YOUR GRENADE!! either with pineapple nade, or stick, u can do this, it's a little more difficult with the pineapple, but, pull the pin, toss the nade down, hit the E key (use key by default), and u will pick the nade back up, YOU have about 2 seconds to release into your enemies face.

ALWAYS, yes ALWAYS drop MG ammo by an MG'r, they will love you for it.
H is the default drop key for MG ammo, this ammo also works for snipers.
Flashlight, GREAT to use for signaling...
Voice comm, PLZ dont stuff yoru mic down your throat!!!!!

Rushing is ok, WHEN the time is right, THIS IS NOT Counterstrike 1.6 OR source, it's day of defeat, it takes teamwork!

Melee, gotta love melee in DOD:S

MG tips, ALWAYS know your "Need ammo" keys

wanna type your location quickly when u need backup??? use U for team chat, and type %l  (yes it's an L, as in larry) and it will give your position.

Im always finding myself RUNNING out of ammo, and not getting anyone to drop me any, glad I know that if i hit G, I will drop my current weapon, and then PICK up another!!
this wasn't the case in the early beta's, you were stuck with what you were stuck with!

enable your -dev console, and enable fast switching....
u can do this under options>controls>advanced in your steam splashboard.

dev console will allow to use your ~ key, and "bring down the console", in the console, u can adjust a few things...

cl_maxrate 9800
net_graph 3
fps_max 300
name "your name here"
sensitivity 12 (whatever u may want your sensi)

Fast switching IS NOT CHEATING, it's a part of the freekin game, so, enable it, and when u pop off a sniper round, scroll your mouse wheel up once and back down, you wont have to go thru the bolt action sequence and POP u can fire again!

Also, whatever you do, DO NOT BLOCK other players, there is a BIG box of clipping around a player, if you get "clipped" it means you've gotten stuck on the other persons polygons. One has to laydown, and MAYBE the other jump alot, and get free, if FF is on, Shoot the sorry bastard that blocked you.

NEVER EVER run in front of an MG firing when FF is on!!!! IF YOU DO, FORGIVE IT, coz it your OWN FAULT, if you can't see/hear that mg going, YOU NEED  A NEW VID CARD and SOUND card.

MG'rs, if your spraying, and you take a break, hit the x key, and then 1 key, it will say "Go GO GO!

VOICE KEYS, x,v,c will bring up interesting voice commands. There are hand signals also, default key, i forget, i've remapped my keys, but it will bring up a gui, and say "Hand Signals" I don't use these, voice signals r good. (not talking about using your microphone0

NEVER EVER EVER pass up someone trying to cap a flag if it takes 2 to cap it, this makes u a tard if u do.... NOW, also, NEVER PASS UP A FLAG period, that needs captured.

This is all I can recall at the moment, but I just typed this in five minutes.
I'll be going to play at "The Sanctuary" in a bit, and my ingame name is "BathroomSinK"

anyone in any DoD:S clans?

looking for dod:source easter eggs, i know them all from dod classic

anyway to just buy DOD:S without buying it online?

i don't have a credit card. i rather buy in-store.

Here is a direct dl of S.M.I.L.E.

it's zipped, virus scan it, it's clean, great screenshot utility hard to find now.

http://home.Comcast.net/~stevenchayes76/Smile.zip

there isn't just a box for dod yet... that i am aware of..

if you find it, POST IT HERE, i've searched google and everywhere...
either go get someone to let you use their card, or go buy CS:S again..
and, IF YOU DID buy that CS:S that is in those links, then you have DoD:Source.