Well, I haven't had any experience promoting ringtones but I've promoted other products. Here's a sample game plan:
1) Find WHERE on the Net your target customers are already hanging out discussing YOUR product. Usual suspects: forums, blogs, ezine, article directories that discuss your product category, guestbooks for sites that discuss that category, etc.
2) Do not SPAM. Spam is too salty anyway. Most people would like it with some bread, some cheese, maybe mustard or some mayo, definitely some lettuce. At that point, it's no longer spam but a nice yummy meal. This might sound funny but it is very important to realize that SPAM is bad but CONTENT is good. Know how to transmute SPAM to CONTENT. Other categories of spam = repetition and highly obnoxious marketing. So in addition to CONTENT, a lot of CONTEXT must be used.
How to do this? Have custom articles about your product category written with your target audience in mind. Read their posts/messages. Figure out WHAT their concerns are. TAILOR your articles and in context marketing materials to those concerns.
3) Distribute your CONTEXT CONTENT promotional materials appropriately. No "bombing". No repetitive postings, etc etc. Participate in the discussion. Then quote part of your article or link to it and paraphrase. The key is to PARTICIPATE and CONTRIBUTE.