Yes, there are many ways to do this. I would start by talking to the company that you currently use for network hardware; they almost certainly have something to suit your needs. If you're just looking to load-balance outgoing requests (ie., surfing the Web), then it's actually pretty easy. I'm not sure if you're an enterprise or a small business, or what bandwidth you have, so I can't recommend a particular product. Regardless, at the low end, it can be done with several products priced under $500. Do a search on "load balancing" and "Internet access."
If you're looking to load-balance incoming requests (ie., you host your own Web site), then you can choose between having separate IP addresses assigned by each of your two ISPs and using round-robin DNS, or having a single ISP range that both ISPs route to you. Round-robin DNS is easy to setup, while owning your own IP range requires that you be listed in the Internet's BGP tables. That's not so simple, and if this isn't making much sense, then you'll probably need to hire some outside help to set it up.
This was first published in November 2003