It's also a de facto standard, at least in the enterprise space, so an additional benefit to us was that most of the sales folks we hired were familiar with it already.
Currently Exchange email only, but Gmail support is nearly done.
Another thing is scheduling SF meetings/events. In order to invite anyone, they need to be inside our system as a user or contact. Most of the time when I'm scheduling a call, I need to end up adding a new contact because they're not in our system (and I don't think it's reasonable to expect everyone I talk to to be in there as a contact).
If Salesforce would reconsider the UX around their calendar, I would love them. I'm a UX designer myself, and my company uses SF. I typically use it when reaching out to clients to schedule calls--and I avoid it otherwise.
As a company we use Mixpanel + Salesforce and did an integration track product usage and can easily see it when contacting users/companies.
Mixpanel is also good for drip marketing, but depends on if you people are logged in or not. Check out Intercom.io or Customer.io depending on what kind of users you have.
You need to start hiring another sales rep too if you're handling 100s of leads by yourself.
You should begin building a qualification framework to understand which leads are valuable and worth your time: Do they have budget? Who has the authority to get this deal done? Do they have a serious need? When will they buy if everything about your product was perfect? And any other unique factors related to your business. Then, get this information into Salesforce!
It's probably time to start using marketing automation/drip campaigns to keep your leads warm too.
Depending on how long your phone calls/meetings run - you'll usually only be able to handle 5-6/day assuming you're doing this full-time so you should consider calculating how many things you can juggle at once.
Use CRM to build a forecast so you can measure your effectiveness. A forecast is as simple as taking the amount of money you might make from each customer that month and multiplying it by the probability you'll close that customer. That'll force you to prioritize.