One way I get sentences for my flash card decks is using
kanjiscripts, a collection of
ruby scripts that play with data from Tatoeba. Check out this search engine for Japanese-English sentence pairs. You search by Japanese character strings. The output is a text file where each line has a sentence in Japanese (kanji), Japanese (kana), and English. You can easily import this data into Anki.
If you're studying a list of single character kanji, you probably want to learn some words that contain those kanji. Feed your kanji list to
kanjiscripts and the output will be a list of sentence pairs oriented around those characters. Import this sentence list into Anki and have fun studying!
Most commonly-used kanji are in many sentences, although some obscure kanji are not. All of the elementary school kanji are used in example sentences with English pairs in the corpus.