You might take a look at the Tropicalesque Forum, right here in the GardenWeb. I'll bet that you find lots of ideas over there.

One VERY tropical looking plant would be the Castor Bean plant. Gorgeous foliage. The entire plant (especially the seeds) are very toxic, so this is not a plant for a household with curious children or chewy pets.

Annual hibiscus would be a good choice, especially with their bright colors.

Here is a link that might be useful: Let's go to the Tropicalesque Forum!

Datura!!!

This plant is just wonderful! The foliage is a very attractive blueish-green with nice-sized leaves, and the plant has a bushy form. The flowers are HUGE, opening at dusk, and oh the fragrance!!! If you let it go to seed, the coolest-looking seed pots appear - they look like some sort of Medieval torture ball.

Datura performs best in full sun. Will tolerate part-shade but won't get as bushy or floriferous. Also performs well in pots, but do get bushier in the ground.

One caveat: The plant is poisonous, so if you have pets that like to occasionally take a nibble out of plants, proceed with caution, and especially re-think this option if you have small children.

I second Ricinus; don't be put off by their toxicity - lots of garden plants are poisonous. Also...
- foliage Amaranthus - 'Early Splendour' and 'Illumination'
- Zea mays 'Quadricolor';
- Pennisetum 'Purple Majesty';
- Bananas and Cannas are so fast-growing that you can use them as one-season bedding plants (they can be overwintered as dormant rhizomes);
- Hibiscus acetosella - again, so fast-growing it can be used as an annual;
- Colocasia (sold as eddo/taro tubers for eating, in supermarkets - start them off in pots in a warm place, give them plenty of warmth and moisture and they'll grow huge).

For more ideas, have a look at this on-line catalogue:
http://www.jungleseeds.co.uk/SeedOrders/enter.html
- not to buy from, but just to get ideas.

Now I'm going to take a look at the Tropicalesque Forum to get some ideas myself!

Thanks for the ideas, I have grown Datura before and it was full of what I think was spider mites, it is really impressive though, so maybe I will give it a another go. I also have had lives lies bleeding never thought to put it there.
Thank You again
Janet

Here is a Datura that is native here, and it came up all by itself. They are not exactly tropical looking, but nice and fragrant nonetheless.

{{gwi:8303}}

You could also use Mirabilis Jalapa. They can become nice size shrubs within one season.
{{gwi:8304}}

And there is also this Amaranthus Caudatus. It's dark color really contrasts with green foliage. It is also very versitile, i let some grow tall and branch out densely, and i also mow over some and they creep along the floor forming a dark colored ground cover. It's a native of Tropical America but has naturalized here in California, it comes up every year along with all of the weeds.
{{gwi:8305}}
{{gwi:8306}}

{{gwi:8307}}

You could also try Impatiens Balsamina
{{gwi:8308}}

Zonal Pelargoniums
{{gwi:8309}}
{{gwi:8310}}

Lastly, you could grow Brugmansias. They are relatives of Daturas, but are much larger and much more fragrant. People in colder climated put them in the ground in the spring, and come fall, they trim them and overwinter them indoors. Even with all of the root disturbance, they grow with a vengance and can become large shrubs up to 10 or 15 feet tall over time.
{{gwi:8311}}

{{gwi:8312}}

Caladium can also be grown as annuals