You might want to try www.dns2go.com or www.dydns.com or www.zoneedit.com
... or www.google.com/search?q=dynamic+dns+services
I use dns2go (paid - reasonable price - good service), zoneedit is free it appears, but I have not tested it.
Usually your ISP will want you to open a commercial account to provide you with a static IP address (read big bucks...), usually a dynamic DNS solution is cheaper unless you require the bandwidth up of a commercial account.
Though most "dynamic" addresses remain the same most of the time anyway on cable, but change more often on DSL I have found.
Actually, My IPs are static. I've had the ip 209.186.148.197 since October, 1998. Charter Sent me a bogus letter telling me I had to turn in my current (non DOCIS) modem for an IMPROVED(DOCIS) modem. This will allow them to take away my static IP address and be NO benifit to me. That's what Charter calls improved.... They said I needed to call by last weekend or my service might go out(it's a lie, they don't plan to discontinue service, they just want to scare me into changing modems, these are the modems they now use for their business customers...) My connection is still up. What happened is I called tech support and he noticed I still had a com21 ant that triggered the form letter. But I have better things to do than deal with charter...
I'm currently changing providers because Charter Communications wants to take my Static IP away(unless I get a business plan.($79/month. 1 static ip, 1500/256))
My new provider will give me 1500/256 for $59/month with 5 static addresses. They also do not block ports or do the other junk BellSouth does.(one static address is $5/month, 5 Static is $10/month)
That's why I'm moving my service. The problem is the connection is IFITL and it was supposed to be live by now. But BellSouth screwed up the connection. It should be fixed by Friday.
Anyway, I have already gotten Direct TV installed and as soon as Bellsouth fixes their mistakes, I'll dump Charter completely.
And if any one wants to know how I feel, RUN AWAY from Charter Communications. They bite. The only reason I stuck with them is I was grandfathered in a cheap plan(that's how I got the static ip).
I'm gonna pay a lot more for TV/ISP, but my family has already agreed that it's worth it.
Charter SUCKS,
jd