Does anyone here know of a free invoicing solution?

So far I've tested the waters with Zoho Invoice, which I think is a really sharp service, but frankly their pricing structure has a flaw. See, they charge you different rates depending on how many invoices/estimates you send out in a month. Basically this scheme penalizes the types of business that do smaller jobs more often. For example, a friend of mine has a video production company, and they may only have four or five clients a month, in which case the free account would probably be enough for him. I, on the other hand, can have four or five clients in three or four days, I'm just not putting as big figures on my invoices. Maybe it's just me, but I don't think I should get penalized just for the structure of the business I'm in.

I also feel like my web space is going to waste. I'm too busy now to keep up my personal website, and aside from selling off a portion of it to clients, I'm not using it for anything. I figure there has to be some open source solutions out there, or at least some one-time fee solutions.

I don't have a lot of requirements. I just want to be able to easily create invoices and either print them out or email them off to clients. Ideally there would be an offline component that would let me print off an invoice in situations where I didn't have internet access, but that's not essential.

Any suggestions?