What sort of songs would you say were modern day classics? Starting from, say 1990 up to the present day, are there any songs which you think deserve to be remebered for ever, and could be counted as some of the best songs of all time?

My first choice immediatly has sprung to mind -

REM - Loosing My Religion

What would your choices be? :)

"Smells Like Teen Spirit" by Nirvana will probably be remembered for a long time.

I'd pick these for starters:
No Rain/Blind Melon
Don't Speak/No Doubt
Smells Like Teen Spirit-Come As You Are/Nirvana
Domino/Kiss
Fire Woman/The Cult

And on the rap front:

Ain't Nothin But A G Thang/F*ck With Dre Day -Dr. Dre

Murder Was Tha Case -Snoop Dogg

I Get Around/Keep Ya Head Up/Dear Mama/Changes -2pac

Gangster's Paradise -Coolio

I'd also choose " Loosing my religion ". I still hear it on the radio these days.

for all the punk fans:

NOFX - The Decline

never will and never should be played on a radio station

Thought of a few more:

Oasis - Don't Look Back In Anger
The Bluetones - Slight Return ( even though nobody seems to have heard this song, it is still one of my all-time favourites!)
Lisa Loeb - Stay
Paul Weller - You Do Something To Me
Nenah Cherry and Youssou N'Dour - 7 Seconds
Stereophonics - Just Looking
Jenifer Paige - Crush

... and I completly agree with those who mentioned 'Smells Like Teen Spirit' :)

I would choose:

"Walk On" by U2
"November rain" by GNR (Hey you did say 1990+)
"In to the great wide Open" - Tom Petty
"Name" - Goo Goo Dolls
"Other side" and "Under the Bridge"- RHCP
"Winds of change" - Scorpions
"Something to believe in" - Poison

These are songs which I think SHOULD be classics, even if they don't carry that universal recognition which a good classic song should. I grew up with these songs and they still hold a certain resonance for me after several years (which is something else a good classic song should do, I think).

One Way - The Levellers
Screamager - Therapy?
Temple of Love - Sisters of Mercy
Unfinished Sympathy - Massive Attack

Lets see songs that should be remembered as classics from 90+ up:  Fly-Sugar Ray, Come As You Are- Nirvana, I'll Make Love Tou-Boyz II Men, Spiderwebs-No Doubt, Enjoy The Silence-Depeche Mode, Are You That Somebody?-Aaliyah, Waterfalls-TLC, Are You Gonna Go My Way-Lenny Kravitz, Save The Best For Last-Vanessa Williams, Another Sad Love Song-Toni Braxton, Under The Bridge-RHCP, Glyceorene-Bush. Some of the Lesser known songs should be classics: Digital Bath-Deftones, Rock Superstar-Cypress Hill, Blast From the Past-Talib Kweli & Hi-Tek, Start With-Seaweed, Stone The Crow-Down, Trust-Megadeath, Angels Son-Lejon From Sevendust w/snot, If You Love Me-Mint Condition, Sour Girl-Stone Temple Pilots,  Yesterday-Shanice, Can't Wait One Minte More-Siv, No One-Cold, Free-Vast, Overcome-Live, Digital-Orgy, They Say Vision-Res, Warning-Green Day. Well thats all for now.