Extensive material here from Grammar Bytes! Good explanation of the rules, and then several pages of interactive exercises.  The exercises are also available for download as .pdf files.

"Rules for fixing comma splices and fused sentences," Grammar Bytes.  Robin Simmons.  http://www.chompchomp.com/rules/csfsrules.htm

Exercises:  http://www.chompchomp.com/handouts.htm

A helpful handout from the University College Writing Workshop at U. Toronto.  This page on comma splices helps writers understand different techniques for correcting a comma splice, as well as how not to correct a comma splice.

"Fixing Comma Splices," Jerry Plotnick, University College Writing Workshop, University of Torontohttp.  http://www.utoronto.ca/ucwriting/commasplice.html

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Grammar Girl's podcasts are educational and entertaining.  She uses real-world examples in her explanations, and invites questions from her audience. Her bit on the comma splice is quite good, with helpful tips like "consider a semi-colon a sentence splicer."

"Comma Splices," Grammar Girl's Quick and Dirty Tips for Better Writing.  http://grammar.qdnow.com/2007/03/15/comma-splice.aspx

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Tina Blue's discussions of grammar problems, like the comma splice, are written in essay style.  Blue speaks in a friendly, easy tone, and while she helps writers correct their grammar problems, she also helps them better understand the writing process.

"What is the comma splice, and how do I fix it?" Tina Blue. Grammar and Usage for the Non-Expert. 2000. http://www.grammartips.homestead.com/splice.html

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