If you don't have sensitive notes, and don't mind the requirement of needing a wifi/EDGE connection, check out Evernote for the iPhone/mac/pc/web (the iPhone client is free). It's a great way of saving notes, web page snippets, images (even from the iPhone camera), etc.. Your notes get synced to Evernote servers, and then to other macs/PCs. On macs/PCs, your notes also get mirrored locally, and so you don't need an internet connection to view/search them. However, on the iPhone, nothing is stored locally, and so a wifi/EDGE connection is needed (hopefully, they'll get rid of this requirement, someday).
More features:
- On macs and PCs, searching is fast. It's almost like having a personal google, but faster.
- On PCs, tablet input and tablet PCs are supported, and so you can enter notes using handwriting.
- Voice notes are supported on the iPhone.
- As your notes are also stored on Evernote's servers, you can view and search them using a browser.
- Notes can be encrypted. However, creating encrypted notes is only supported on macs/PCs; the current iPhone client can only view them, and not create them.
Downsides include:
- There is no usable TODO function. While you can create notes that contain a checkbox, it's not terribly usable.
- Notes can only be organized using different notebooks and tags (multiple tags per note are allowed). Folders and sub-folders within a notebook are not supported.
- From a mac/PC, browsing notes is cumbersome. While you can browse, looking at notes is ugly, and the UI has confusing scrollbars.
- Some people may worry about notes being stored on Evernote's servers. For me, this is a non-issue, as I don't store any sensitive information in Evernote (I've been using eWallet for that, as I use a PC, but mac users would probably use 1password, instead).
- The free Evernote accounts transfer notes using plain unencrypted http. You have to upgrade to the paid accounts to get transfers via SSL.
For me, Evernote has replaced del.icio.us and most of my bookmarks. I now dump web pages into Evernote, and let searching find my "bookmarks" (Evernote keeps the web page URL when you save a web page snippet). I now only keep around a bookmarks toolbar for my most frequently-used bookmarks.