One of the things I enjoy doing is capturing what God speaks to me as I read the Bible. This is the primary way that I "journal." When a Scripture stands out to me or the Holy Spirit prompts me with something that I'm reading, I take extra time to meditate and pray about that Scripture or particular passage. It really helps me to also write out what God is laying on my heart regarding those verses. I find that as I begin to write, that God begins to reveal more. This is often how Scriptures come ALIVE in my spirit. God uses this process to give me greater revelation of His Word.
I've recently started to use the website, momolog.com as my journaling resource. It's a free service that allows you to keep daily/regular journals and memos. (You must have a Google account to access it, but you can set one up very quickly if you don't already have one). It's been working great for me so far. I also like the way you can "tag" each entry with keywords that relate to the topic you're writing about. You can then search the keywords to find specific things you've written about in the past. This is a great source of help, because many times my sermons and teachings will come from the times God has spoken to me through the Bible. Now I have an easy way to capture those thoughts and recover them quickly when I need them.
If you're an iphone user, there's a momolg app that's available, but it does cost $4.99 (at the time of this posting). I haven't used it yet, but if you search "momo" in the app store, you'll find it.