TLSBooks.com, Education.com, Fun2Write.com, WorksheetFun.com and KidsLearningStation.com are all websites that provide printable worksheets appropriate for preschool children. These free worksheets typically focus on either recognizing a printed letter or tracing the letter.
TLSBooks.com features sets of worksheets for practicing the alphabet. Each set of worksheets includes a description of the target skills. For instance, one set of worksheets promotes letter recognition by having children draw a line from an image of a farm animal to the letter with which the word begins.
Education.com also offers worksheets for practicing letter recognition. The site includes a whole set of "...is for..." worksheets. For example, on the "R is for..." sheet, children color in the letter R and pictures of words that begin with R to reinforce recognition of that letter and its sound. Another worksheet has them coloring different letters in different colors to make a picture.
Fun2Write.com has another version of the "...is for..." worksheets. In this case, children trace a single letter over and over on a given line before coloring in the picture. WorksheetFun.com also has tracing worksheets. Children have space on these worksheets to trace the entire alphabet in both capital and lowercase letters.
KidsLearningStation.com has all of the above worksheet types as well as games. For example, the letter matching game encourages children to match capital and lower case letters.