[FONT="Comic Sans MS"][COLOR="#300090"]Seam:
You can use a hook similar to how you use a yarn needle. Just put the hook through the same stitches/loops you would the needle but in the opposite direction so it points toward your yarn end, then YO the hook and pull the tail through.
These have some clear drawings for seaming knit projects:
[COLOR="blue"]http://www.yarnshopping.com/knitting/joining.html[/COLOR] [*Edit: Added then removed link; no image or information on joining/seaming there. :nails: ]
There are many decorative edges that can be done with crochet. Search for projects with edges you like then skip to the end of the pattern where they give the pattern for the edging.
What kind of stitch did you use on the pieces you are joining? There may be a crochet stitch or pattern that is similar in appearance. I may be a knit beginner, but I design my own crochet patterns. If I can visualize the knit stitch you used, then I can give better options for the seam or edge.
Edit to add...
Hidden: A slip stitch can join the knit pieces from the wrong side.
Understated: Try a single row (or round) of single crochet (sc), use 3 sc in the same stitch to go around a corner (one for each side and another for the corner, 3 sc).
Bold: Try a decorative pattern edge with multiple rows/rounds. Scalloped, ruffled, or fringed are just a few choices.