You guys sure don't disappoint! Loads of great suggestions in here, I'll second pretty much everything and add a few of mine:
Warioware Smooth Moves: The 2nd best in the series right next to Twisted on the GBA, the game is absolutely hilarious and loads of fun either alone or with friends! It's motion controls done right.
Wario Land Shake it: Similar to the classic Wario Land games on the GB, GBC and GBA, not quite as good as WL4 on GBA, but I'd say it's easily the 2nd best! It's got beautiful hand-drawn graphics (I wish more modern games looked like it), and if you get past a bit of waggling here and there it plays fine too!
Muramasa the Demon Blade: You can also get it on the Vita in higher resolution, but the Wii version is pretty good too, I haven't played much of it but I loved what I did play, the graphics are once again hand-drawn and I LOVE them, they're gorgeous! It's got a whole lot of parallax scrolling too so that's good, and the combat is so satisfying! If I'm not mistaken It's a Metroidvania style game, and a good one at that!
You can use the Classic Controller with this one, so no waggling required!
House of the Dead Overkill: Want a horror B-Movie turned into an on-rails shooter? This is the game for you! I've only played it once on a friend's Wii, but I loved it so much that I can already highly recommend it!
Resident Evil 4 Wii Edition: You've probably already played it, but let me tell you, the Wii version is the definitive way to play it! Aiming with the Wiimote never felt so natural!
Castlevania the Adventure Rebirth: The last Castlevania game to use the classic linear style, and in my opinion, the last good Castlevania, it's got one of the best soundtracks in the series and the graphics and gameplay are basically what you'd expect from the series on a 480p system, a must-play for any fan of the series who owns a Wii!
Contra Rebirth: Same as the above, except with Contra, it's pretty damn good too! Although you might find it a bit too easy...
Gradius Rebirth: Same as the previous two, but with Gradius, you get the gist of it...
Tatsunoko Vs. Capcom: No list of mine would be complete without a good'ol Fighting game, but this one uses the same engine as Ultimate Marvel vs Capcom 3, but it runs on the Wii, and it does so pretty damn smoothly! Ain't that impressive? Well so is the whole rest of the game! Just make sure you play it with a classic controller or a Wii Arcade Stick, a must-play for fighting game fans who own a Wii!
By the way, hack your Wii, just do it, it's really worth it! Loads of great emulators for it!