You can get some card ideas from manufacturer web sites such as:
Close To My Heart
You can also check out some online stamper communities such as
Two Peas In A Bucket
Stamp n' Scrap
And, of course there are a ton of blogs which feature stamp ideas. One of my favorites is KWernerDesign. She also has a great 3-part Q & A about her card making and technology use. Check it out: Part 1, Part 2, and Part 3. I like her design style because it's simply cute and easy to replicate.
Someone asked me how do I use foam stamps. I use them with acrylic paints to stamp images on cards, scrapbook pages, and craft projects. I used foam stamps to stamp words onto my cork bulletin board in my studio. This is a video from Making Memories on how to use foam stamps. I use the wood handled foam brush instead of the one shown in the video. I also rinse them out and reuse them until they fall apart. Why waste supplies and pollute the environment unnecessarily?