Yes, for my TX1 there is standard Canon's ACK-DC10 AC power adapter kit. It works with my other SD750 Powershot too.
It has just small plastic box that you insert inside the camera instead standard NB4-L battery.
If you look at the battery door you should see rubber cover for adater connectors plug.
THe price is rather steep for ACK-DC10, so as I bought one of those (for around $50), I've used them to come up with my very cheap alternative.
ACK-DC10 provides stable 4.5v at up to 1amp current.
So, what I did (and you can do too) is just took standard NB-4L battery, solder 2 wires to Gnd/+ and insert it into it's normal position in the camera, allowing those 2 wires to go out through that rubber covered adapter hole. Then I took old and unused 4v unused power adapter and properly connected it. It works perfectly.
I don't know about other cameras but TX1 has power regulator on entry, so you probably can provide higher voltage power then 4.5V to it. Be carefull here, and don't take my words as you might burn your cameras power entry.
But logically, if they do have (which they for sure do) power regulator is probably standard range and therefore it could accept anything up to 12V.
On my TX1 I've managed to install 2 rechargable protected 18650 batteries sequentially (each battery is 3.7V, thus giving me 7.4V 2500mah), which gives me around 8-12hours of contant on. So, it's enough for a week and more even with extensive usage without recharging. You can also connect them in parallel, which gives you exactly the same as required cannons(NB4L or NB5L) 3.7v, but with astounding 5000mah (which is more then 8 times more then standard NB4L).
In fact, I'm not even using any wall power adapter to recharge those batteries. I'm just connecting them to USB connector, which is 5V and as batteries are protected, they charge to 4.2v and actually perform that extremely fast.
If interested, use only protected batteries (or protect unprotected ones): here is a deal on good batteries:
DealExtreme: $10.00 TrustFire Protected 18650 Lithium Battery (2500mAh 2-Pack Blue)
BTW: Here is pretty good deal on standard adapter I have, just $29. I've bought the same for $49:
BestBatt.com - Canon ACK-DC10 AC Power Supply AdapterHowever, I wouldn't pay even that if you have old unused battery and old unused AC 4-5v adapter and ready for DIY solution.
