Besides the traditional Nintendo games, what else is exactly exclusive to Wii at the moment?
A bit of research on the internet would do you some good. I suggest you become familiar with IGN Wii (type it in on Google) and be up to date on the latest information.
A list of third party exclusives would be hard to come by, as the list is constantly changing as more developers are being added to that list. Not to mention, many of them are tight-lipped; journalists know about these games but are under embargo and not able to report on them until the developer gives them permission. For instance, IGN Wii's Matt Casamassina has been posting on his personal blog for several months now about several high-profile games that he can't report on just yet. There are many, many stories everyday about developers jumping onto the Wii bandwagon.
As for your anxieties, chill. Third parties had no clue that Wii would become the best-seller and market leader as it is now, and generally thought the PS3 would continue to dominate. They were wrong, and are quickly changing their business strategies. Presently, every system is experiencing a drought, Wii being no exception. Super Paper Mario is really the only good game released in the last week. That isn't to say that third parties aren't totally dropping the ball, as SSX Blur, Godfather, Mortal Kombat: Armageddon, Elebits, etc. have received generally high praises from video game journalists.
Third party games are coming. The creator behind Metal Gear Solid and Suda51 are jointly working on a Wii project. Suda51 is working on No More Heroes. Capcom is releasing RE4 Wii, RE:UC, and Treasure Island (which promises to be a fantastic game.) Sega is reviving NiGHTS, the cult classic from the Sega Saturn. And trust me, there's more.
At the end of the day, though, I know Nintnedo makes the best games in the industry, and they're worth waiting for. I'm certain SMG is going to be a ground-breaking game for the ages. And Metroid Prime: 3 is going to be sublime. And Brawl is the icing on the cake.
For now, revisit a few classics on the VC, or buy some of the legendary titles that were on GameCube (if you haven't played Metroid Prime, please play it; it is the best thing to come out of gaming this side of Ocarina of time). Bust out Wii Sports and have a few casual outings with your family and friends or just enjoy the simple pleasures of fishing on TP (I'm convinced there's a secret waiting for me in that fishing hole, and I'm determined to find it).
Chill. It's all good.
(Pick up SPM.)