Those two just didn't click with me....

[Kikanu]

This is the third time I've tamed Loque, and I recently tamed the green snake (which was simply for bragging purposes, since nobody ever had one from what I saw), but I just can't like them. I have Arcturis as my Hands-Down awesome pet, and I have Aotona for my Cunning pet for raids (that mana back helps, and the disarm saves tanks in ToC at times). I still have my Springpaw Lynx, which is my all time favorite pet, and was my first one. I even went hardcore RP and went to Zul'Drak, up to Har'koa at the flight path place and released him there. The snake...eh, just tossed it in the Argent Tournament.

I'm at a loss for what I should fill my slots with. Two blank spots BEG for a filler, but I can't choose. It sucks because I feel like I wasted the gold on the slots since I never keep the fourth and fifth pets.

[Verynna]

I know how that is. Sometimes I tame a pet thinking it's the right one, but then it just doesn't feel right.

You could fill those slots with pets that might disappear for preparation in Cataclysm, such as the teal scorpid and ghost saber. I'd personally always have one useful-but-disposable slot in case of finding a spirit beast, unless you eventually get them all or don't want them.

If you want something else unique, I would recommend a jade owl, purple riding tiger, green warp stalker, or a scarlet hyena. Just a few of my old favourites. I've never seen anybody with them (except the warp stalker before WotLK and jade owl during early WotLK, but not anymore), and they look nice as well.

[Kikanu]

I used to have a Jade Owl, back in BC I used a white warp stalker, and I tried Hyenas, but they never really felt fun to use (save for the owl, but I got the blue parrot in place of it). As for the Ghost Saber, I'm not really too keen on that. It's unique, but the color of its skin isn't interesting; I'm not a leopard fan. If it were a ghostly Springpaw Lynx, I would grab it in a heartbeat. Scorpids just don't interest me, sadly.

Blizz should just hurry up and give us a show of the new tamable pets, or give us the Cataclysm Alpha, see some of them new beasts D:

[Rhyela]

Are there any pets that just "look good" to you? If you can't think of anywhere you'd actually use two new pets, then why not just get some pets that are nice to look at while you parade around in Dalaran?

Do you have any interest in PvP, even if only casually? If so, you could start taking a look at some pets that might be useful in PvP and go from there. I found out that I actually rather like the green Outlands chimaera after I tamed him.

Or, if you have a color that's kind of a theme for your hunter, try finding pets that match you! I'm really weird when it comes to this, though now only Apollyon matches me. But at one time, I had at least three or four pets who had a bright green hue to them.

These are just ideas until Cataclysm arrives, then you can release those two filler pets and go get something new and juicy!!!

[Palladiamorsdeus]

Yup yup. If you've got your functional, then just go with looks. My fifth slot is my 'revolvoing door' slot. Day before yesterday it was a bear. Yesterday it was a dragonhawk. Today a spore bat. Tomorrow, who knows?

[Tilo]

ghostly Springpaw Lynx

^

Now that'd rock!

But others have mentioned suggestions already; if your main pets that you use consistently are covered; then browse the looks, pick a few you might enjoy, try them out, or go for the rare "extinct" ones just to have till Cata... I'm sure you'll figure something out