A flower bed often benefits from being hemmed in by good edging plants. Fountain shapes or tidy mounds are my favorites. Here are a few plants that fit the bill.
Daylilies - you can see how nicely the yellow Stella d'Oro daylilies edge the front of the tiny bed below. This picture is from my tiny Santa Clara, CA garden. RIP - we moved in May 2007 and the next renter probably let it dwindle away to weeds. I had just 3 years there in mild-climate-heaven, and a very strict budget (um, more like NO budget). So my garden was created with starts from generous friends. Good thing the growing season was so long there - more than double our season here - so things grew a lot each year.
I prefer daylilies - like Stella - whose flowers are borne on scapes that are similar in height to the leaves. I really don't like the ones whose flowers tower above the leaves on huge stalks.
Liriope muscari (clump-forming liriope) - the following photo is of a small plant I ordered from Bluestone Perennials a couple of months ago. I'm keeping it in a pot on my kitchen window over the winter in hopes that it will grow to a decent-sized plant during the months that it would otherwise be sleeping outdoors. These plants are very sturdy (not troubled by pests, OK in sun or shade, drought-tolerant once established), though marginally hardy in my zone 5. They're evergreen in milder climates, so I'm not sure if it will just turn ugly yellow or die back to the ground here next winter. I won't find out this year, check back in spring 2010 to find out!
Thrift or Sea Pink - the following picture was taken in November after numerous frosts, but you can see how the plant is still trying to flower! There's just one plant here, but you can imagine how nice a row of these would look along the edge of a flower bed. These plants love sun and are evergreen in mild climates. I especially love the types that have hot pink flowers. They're fun to include in a small bouquet or nosegay.
Heuchera - here is a photo of Green Spice heuchera, also taken in November. All of my hostas are long gone, but the heuchera leaves stand up to the cold longer. Heucheras like to avoid intense sun and heat, and have tiny flowers on tall stalks in summer. I like to use heuchera leaves to surround a little nosegay of flowers, tied all together with raffia or floral tape. I also have heucheras with plum-purple leaves and true-green leaves. Love em all.
Other plants that would be good for edging include: campanula 'Blue Clips', small hostas, violets or annual alyssum. Sorry I don't have pictures of those to post.
Note to self - I need more & better pictures to post! I'm asking Santa Claus for a digital SLR camera for Christmas, then maybe I'll request a macro lens for Mother's Day (though I was going to ask for a dogwood tree instead . . . hmm). So next year I'll be sure to take lots of pictures, hopefully better ones than I can capture with my point-and-shoot camera now. Of course, June 2009 will make just 2 years since we bought this home, at which time nothing worth keeping was growing in the flower beds (exceptions - 1 dogwood and 2 lavender bushes - everything else got trashed or will be trashed soon). So my yard as a whole won't be gorgeous for some years ahead. But individual plants should start looking good. My mantra - patience is still a virtue!