Well I recommend Super Mario Galaxy 2 and The Legend of Zelda: Twilight Princess.

Monster Hunter Tri is great if you like action RPGs like the recent Phantasy Star titles.

You can't go wrong with any Mario title, really.

I recently got Punch Out for Wii and it's really fun. It's a revival of the old NES feel, but it also breathes new life into the game's characters.

As for WiiWare, I've played the PC version of Toribash and that's good.

I love tatsunoko vs capcom you should try it

Pokemon Rumble is fun and it is multiplayer.

I would like to recommend the "Mario Kart for Wii" game. I've played it, and I don't always like racing games, but that game was awesome. Its the best newest Mario Kart next.

Boom Blocks is a good party game. if you like racing type games try exitebike: world rally (i think thats the title i dont own it my cousin does) its on wiiware. all bit.trip games are good for people that like old school types of games, i only have the demo but its really good. wii sports resort is good to for casual gamers. same thing for animal crossing city folk. for action games stick with punch out for wii not the wii ware one and another good multiplayer party game is new super mario bros wii. i know im leaving some of my favorites out but this is a good list.

i too would recomend mario kart it is fun and an enjoyable game on wi-fi

i would defienently say tatsanuku versus capcom really fun game and lots of old school favorites. MEGAMAN!

billythekidmonster : agreed. i remember we rented that game and it was really fun and sooooooooo many characters to choose from. and all the combos are easy to do

you might enjoy metroid other m, punch out, mario super sluggers, or even new super mario bros. wii! you could also get warioware DIY showcase

I am loving Super Mario Galaxy 1 at the moment. I also really like Okami.

Here's a few good ones that I enjoyed:
New Super Mario Bros Wii
Boom Blox
Sam And Max Season One and Season Two (season 2 is called "Sam And Max: Beyond Time And Space")
The House Of The Dead Overkill
Resident Evil: The Umbrella Chronicles
Resident Evil: Darkside Chronicles
Super Mario Galaxy 2

Some WiiWare games that are good are the Strong Bad series. Great if you like point-and-click adventure games, plus the series is very funny.

I would recommend mega man 9 on wiiware for 1000 wii points.

I've been informed that there's a Pokemon Stadium for the Wii console? If this is true I recommend it.

A list of my personak favorites include:
New Super Mario Bros. Wii
Super Smash Bros. Brawl
Mario Kart Wii
Donkey Kong Country Returns
Okami
Both Super Mario Galaxy Games
Legend of Zelda Twilight Princess
Wii Sports Resort
Guitar Hero 3
and

WiiWare includes:
Legend of Zelda: Ocarina of Time
StarFox 64
Kirby's Adventure
Ice Climber
Kid Icarus
Donkey Kong
and
The MegaMan Series

Monster Hunter Tri is a great game if you really like hardcore games and haven't tried it yet. I highly recommend it if the others haven't convinced you yet.

One other idea is Red Steel 2. It isn't as great as some others, but if you have a Wii Motion Plus already and you can find the game relatively cheap, Red Steel 2 actually isn't half bad, if you can get over the relatively slow start due to the lack of learned moves.

Also, if you are a Star Wars fan and like a good Star Wars story, or you just simply want to throw Stormtroopers out the airlock with the force and destroy random stuff in the environment, then you might want to try The Force Unleashed. The gameplay gets a bit repetitive after a while, but you can always use a new power or combo if the one you're using gets old. The story is also very interesting, including a massive 'You've got to be kidding me...' moment in the middle that is not to be missed if you consider yourself a Star Wars fan.

For the most part, the rest of the posters have given out some good ideas, so I'll leave it at that.

EDIT: some of the text went over the bright spot in my layout, so I'm editing it out so you can read my post.

I suggest getting the legend of zelda twilight princess or Dragonball z budokai tenkaichi 3. The wiimote controls for dbz bt3 are hard at first but once you get it down it is very fun.

Wii party for me. It looks really stuipid when you first play it, but there are a lot of games to play and all of them are mii compatable. My favorite is when you play bingo and instead of numbers they composed of miis from your collection.

So yeah the obvious, Galaxy 1 and 2, Metroid Prime 3, Other M, DKC Returns, Kirby's Epic Yarn, New Play Control Pikmin, yadda yadda yadda...
but I must agree with WSF, the Wii version of Force Unleashed is the best one, and the controls work really well.
Namco Museum Remix is a good one too, especially for the added bonus of all those arcade originals.

One of my favorite Wii games that either no one seems to like or know about is No More Heroes. A strange game? Yes. It's like Killer7. It will be on the ps3 I hear, but it came out on Wii first. I don't have the second game just yet, but I would probably like it because I like the first one a lot.